KR20230019095A - Mode-selective coupler for reducing frequency bumps - Google Patents

Abstract

Systems and techniques that facilitate mode-selective couplers for frequency collision reduction are provided. In various embodiments, a device may include a control qubit. In various embodiments, the device may include a first target qubit coupled to the control qubit by a first mode-selective coupler. In various examples, the first mode-selective coupler can facilitate A-mode coupling between the control qubit and the first target qubit. In various embodiments, the device may include a second target qubit coupled to the control qubit by a second mode-selective coupler. In various embodiments, the second mode-selective coupler may facilitate B-mode coupling between the control qubit and the second target qubit.

Description

Mode-selective coupler for reducing frequency bumps

[0001] The present invention relates generally to superconducting qubits, and more particularly to mode-selective couplers for reducing frequency collisions between superconducting qubits.

[0001] The present invention relates generally to superconducting qubits, and more particularly to mode-selective couplers for reducing frequency collisions between superconducting qubits.

[0002] The following provides a summary to provide a basic understanding of one or more embodiments of the present invention. This summary is not intended to identify key or critical elements or to delineate the scope of specific embodiments or claims. Its sole purpose is to present concepts in a simplified form as a prelude to the more detailed description that is presented later. In one or more embodiments described herein, devices, systems, computer implemented methods, apparatus and/or computer program products that facilitate mode-selective couplers for frequency collision reduction are described.

[0003] According to one or more embodiments, a device is provided. In various embodiments, the device may include a control qubit. In various examples, the device may include a first target qubit. In various cases, the first target qubit may be coupled to the control qubit by a first mode-selective coupler. In various embodiments, the first mode-selective coupler can facilitate A-mode coupling between the control qubit and the first target qubit. In various examples, the device may further include a second target qubit. In various embodiments, the second target qubit may be coupled to the control qubit by a second mode-selective coupler. In various cases, the second mode-selective coupler can facilitate B-mode coupling between the control qubit and the second target qubit. In various embodiments, the first mode-selective coupler may include a capacitor. In various examples, the capacitor can capacitively couple a middle capacitor pad of the control qubit to a middle capacitor pad of the first target qubit. In various embodiments, the second mode-selective coupler may include a first capacitor and a second capacitor. In various embodiments, the first capacitor may capacitively couple an end capacitor pad of the control qubit to an end capacitor pad of the second target qubit. In various examples, the second capacitor can capacitively couple an end capacitor pad of the control qubit to a middle capacitor pad of the second target qubit.

[0004] According to one or more embodiments, a method is provided. In various embodiments, the method may include providing a control qubit. In various examples, the method may further include coupling the control qubit to a first target qubit by a first mode-selective coupler. In various examples, the first mode-selective coupler can facilitate A-mode coupling between the control qubit and the first target qubit. In various embodiments, the method may further include coupling the control qubit to a second target qubit by a second mode-selective coupler. In various examples, the second mode-selective coupler can facilitate B-mode coupling between the control qubit and the second target qubit. In various embodiments, the first mode-selective coupler may include a capacitor. In various examples, the capacitor can capacitively couple a middle capacitor pad of the control qubit to a middle capacitor pad of the first target qubit. In various embodiments, the second mode-selective coupler may include a first capacitor and a second capacitor. In various cases, the first capacitor can capacitively couple the end capacitor pad of the control qubit to the end capacitor pad of the second target qubit. In various embodiments, the second capacitor may capacitively couple an end capacitor pad of the control qubit to a middle capacitor pad of the second target qubit.

[0005] According to one or more embodiments, an apparatus is provided. In various embodiments, the device may include a first mode-selective coupler that facilitates A-mode coupling between the control qubit and the first target qubit. In various embodiments, the device may further include a second mode-selective coupler that facilitates B-mode coupling between the control qubit and a second target qubit. In various embodiments, the first mode-selective coupler may include a capacitor. In various examples, the capacitor can capacitively couple a middle capacitor pad of the control qubit to a middle capacitor pad of the first target qubit. In various embodiments, the second mode-selective coupler may include a first capacitor and a second capacitor. In various embodiments, the first capacitor may capacitively couple an end capacitor pad of the control qubit to an end capacitor pad of the second target qubit. In various cases, the second capacitor can capacitively couple the end capacitor pad of the control qubit to the middle capacitor pad of the second target qubit.

[0006] FIG. 1 shows a circuit diagram of an exemplary non-limiting system that facilitates A-mode coupling in accordance with one or more embodiments described herein.
[0007] FIG. 2 shows a block diagram of an exemplary non-limiting system that facilitates A-mode coupling in accordance with one or more embodiments described herein.
[0008] FIG. 3 shows a circuit diagram of an example non-limiting system that facilitates B-mode coupling in accordance with one or more embodiments described herein.
[0009] FIG. 4 shows a block diagram of an exemplary non-limiting system that facilitates B-mode coupling in accordance with one or more embodiments described herein.
[0010] FIG. 5 shows a block diagram of an exemplary non-limiting system that facilitates mode-selective couplers for frequency collision reduction in accordance with one or more embodiments described herein.
[0011] FIG. 6 shows a flow diagram of an exemplary non-limiting method that facilitates a mode-selective coupler for frequency collision reduction in accordance with one or more embodiments described herein.
[0012] Figures 7-8 show graphs of exemplary non-limiting simulation results of a system that facilitates a mode-selective coupler for frequency collision reduction in accordance with one or more embodiments described herein. .
[0013] FIG. 9 shows a block diagram of an exemplary non-limiting quantum computing lattice that facilitates a mode-selective coupler for frequency collision reduction in accordance with one or more embodiments described herein. .
[0014] FIG. 10 shows a flowchart of an example non-limiting method that facilitates a mode-selective coupler for frequency collision reduction in accordance with one or more embodiments described herein.
[0015] FIG. 11 shows a block diagram of an exemplary non-limiting operating environment in which one or more embodiments described herein may be facilitated.

[0016] The following detailed description is illustrative only and is not intended to limit the embodiments and/or the application or use of the embodiments. Furthermore, no information, expressed or implied, presented in the preceding background or summary sections, or detailed description sections, is binding.

[0017] One or more embodiments are described with reference to the drawings, wherein like reference numbers are used throughout to indicate like elements. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a more complete understanding of one or more embodiments. However, it will be apparent that in various instances, one or more embodiments may be practiced without these specific details.

[0018] Superconducting qubits are a promising technology in the quest to build large-scale quantum computing systems. A superconducting qubit has, in various cases, one or more Josephson junctions shunted by one or more capacitors (e.g., quantum mechanical behavior). It can include macroscopic structures that can be expressed. In various examples, a quantum computing system may be formed based on a two-dimensional lattice of superconducting qubits (eg, a quantum computing lattice) in which adjacent pairs of superconducting qubits may be coupled by a bus resonator (eg, a microwave resonator). there is. In various cases, a coupled pair of adjacent superconducting qubits can be entangled through a two-qubit gate called a cross-resonance gate. In various embodiments, the cross-resonance gate generates a microwave pulse and/or tone at a transition frequency (eg, operating frequency and/or qubit frequency) of an adjacent and/or neighboring superconducting qubit, called a target qubit. It can be implemented by driving one superconducting qubit, called a control qubit, using (tone). In various examples, a control qubit may transmit a pulse and/or tone to a target qubit in response to being driven by a microwave pulse and/or tone. In various embodiments, the amplitude of a pulse and/or tone transmitted from a control qubit to a target qubit may vary depending on the state of the control qubit, thereby entangling the two superconducting qubits. That is, the target qubit can undergo qubit rotations, and the speed of the qubit rotations can depend on the state of the control qubit.

[0019] To selectively entangle superconducting qubits, the neighbors of a control qubit (eg target qubits) may have unique (eg sufficiently separated) transition frequencies. A nearest-neighbor-connected quantum computing lattice of superconducting qubits in which all superconducting qubits (e.g., except for those at the border/periphery of the lattice) have four neighboring and/or adjacent superconducting qubits. -neighbor-connected quantum computing lattice of superconducting qubits), 5 unique transition frequencies may be needed (e.g., 4 unique transition frequencies for 4 target qubits and 4 unique transition frequencies for control qubits). Transition frequency of 5). In various cases, a quantum computing lattice can be formed from single-mode qubits; That is, every superconducting qubit in a quantum computing lattice has a single transition frequency (eg a single-junction transmon). In various cases, such a grating may require five uniquely fabricated sets of superconducting qubits to obtain the five unique transition frequencies required for selective entanglement (e.g., A first set of single-junction transmon qubits, a second set of single-junction transmon qubits with a second transition frequency, a third set of single-junction transmon qubits with a third transition frequency, a fourth set of single-junction transmon qubits generating a lattice from a fourth set of single-junction transmon qubits having a transition frequency and a fifth set of single-junction transmon qubits having a transition frequency). In various embodiments, a quantum computing lattice may include tens and/or hundreds of superconducting qubits. When many superconducting qubits are implemented, it can be difficult to reliably and/or consistently fabricate sets of five unique superconducting qubits (e.g., five transition frequencies) due to imperfections in nanofabrication techniques. It can be difficult to keep all of the sets at the desired values). When two target qubits adjacent to and/or neighboring a control qubit have similar transition frequencies, selective entanglement cannot be implemented between the control qubit and these target qubits. This is known as target-based frequency collision. In various embodiments, target-based frequency collisions can negatively impact the performance of a quantum computing system.

[0020] For quantum computing lattices that include next-nearest-neighbor-connectivity as well as nearest-neighbor-connectivity, five or more unique lattices to facilitate selective cross-resonant entanglement More than five distinct transition frequencies may be required (e.g., up to nine distinct transition frequencies are required, so nine distinct sets of superconducting qubits). May be needed; one transition frequency for the control qubit, four unique transition frequencies for the four nearest-neighbor target qubits, and four for the four next-nearest-neighbor target qubits. one or more unique transition frequencies). In such cases, target-based frequency collisions may be much more likely to occur.

[0021] Those skilled in the art will understand that what constitutes a frequency collision may vary depending on the implementation details and/or operating context of a quantum computing system. In various embodiments, one skilled in the art understands what threshold of similarity at transition frequencies can constitute a frequency collision and/or what threshold of dissimilarity at transition frequencies can constitute a frequency collision. You will understand if a collision can be avoided.

[0022] Several approaches to reducing the number of target-based frequency collisions include reducing the connectivity of a quantum computing lattice (eg, reducing the average number of neighbors for a common qubit in a quantum computing lattice). A quantum computing lattice with reduced connectivity, called a low-degree lattice, may be less likely to experience frequency crashes, but may also be less resilient to errors, and thus quantum error correction codes. codes) may be required. In various embodiments, systems and/or techniques for reducing frequency collisions without reducing grid connectivity may be desirable.

[0023] Various embodiments of the present invention may solve one or more of these technical problems. In various embodiments, embodiments of the present invention may provide quantum computing lattice architectures capable of reducing the statistical probability of frequency collisions without correspondingly reducing lattice connectivity. Specifically, in various embodiments, embodiments of the present invention provide a quantum computing lattice based on two-junction transmon qubits coupled by mode-selective couplers. may include generating

[0024] In various embodiments, a double-junction transmon qubit may be a superconducting qubit comprising two capacitively-shunted Josephson junctions coupled in series (e.g., a double junction transmon qubit). - A junction transmon qubit may be formed by two single-junction transmon qubits connected and/or coupled in series). That is, the double-junction transmon qubit may include a first Josephson junction and a second Josephson junction, wherein the first Josephson junction is coupled in series between a first capacitor pad and a second capacitor pad, and a second Josephson junction A Josephson junction is coupled in series between the second capacitor pad and the third capacitor pad. In various embodiments, the second capacitor pad may be referred to as a middle capacitor pad of a double-junction transmon qubit, and the first capacitor pad and the third capacitor pad may be a double-junction transmon qubit. may be referred to as end capacitor pads of In various examples, a double-junction transmon qubit may support and/or exhibit two distinct excitation modes, an A-mode and a B-mode. In various embodiments, these two unique excitation modes may have two different spatial symmetries and/or two different transition frequencies (eg, an A-mode transition frequency and a B-mode transition frequency). In various examples, a double-junction transmon qubit may be encoded in A mode (e.g., thus having an A-mode transition frequency) or encoded in B mode (e.g., thus having a B-mode transition frequency). -can have mode transition frequencies). In various embodiments, short microwave pulses can be used to switch a double-junction transmon qubit between encodings (e.g., a suitable microwave pulse can be used to switch a double-junction transmon qubit to switch the doubly-junction transmon qubit from A-mode to B-mode and/or from B-mode to A-mode). In various embodiments, and as described in more detail below, mode-selective coupling is performed on adjacent and/or neighboring double-junction transmon qubits to facilitate selective cross-resonant entanglement. can be implemented between them. In some cases, mode-selective coupling can be implemented between next-nearest-neighbor double-junction transmon qubits to facilitate selective cross-resonant entanglement.

[0025] As mentioned above, a quantum computing lattice comprising bus resonators between single-junction transmon qubits may require sets of five uniquely fabricated qubits (e.g., control with one set corresponding to a qubit and 4 unique sets corresponding to 4 unique target qubits, for a total of 5 unique transition frequencies). On the other hand, in various examples and as further explained throughout this disclosure, a quantum computing lattice comprising mode-selective couplers between double-junction transmon qubits is uniquely fabricated with three rather than five (e.g., a first set of doubly-junction transmon qubits having a first A-mode transition frequency and a first B-mode transition frequency, a second A-mode transition frequency) A second set of double-junction transmon qubits having a frequency and a second B-mode transition frequency, and a double-junction transmon qubit having a third A-mode transition frequency and a third B-mode transition frequency. as the third set of , for a total of 6 unique transition frequencies).

[0026] In various cases, this reduction in the number of sets of qubits that must be fabricated in a quantum computing lattice can reduce the probability and/or prevalence of target-based frequency collisions. Finally, in various embodiments, nanofabrication and/or microfabrication may result in inherent and/or unintended changes that make it difficult to fully control the structural properties of superconducting qubits, i.e., the transition frequencies. may include process variations. As the number of unique sets of superconducting qubits fabricated increases, the differences between the structural properties of one of the unique sets of superconducting qubits and the structural properties of the other of the unique sets of superconducting qubits become more pronounced. Fewer and/or smaller. In some cases, inherent and/or unintended process variations during nanofabrication and/or microfabrication may cause these pre-existing-less and/or already existing-less and/or already-existing process variations in structural properties, which may cause target-based frequency conflicts. may further reduce existing-lesser differences (e.g., the structural properties of one of the unique sets of superconducting qubits are too different from the structural properties of another one of the unique sets of superconducting qubits). can be similar). On the other hand, as the number of unique sets of superconducting qubits fabricated decreases, the structural properties of one of the unique sets of superconducting qubits and the structural properties of the other of the unique sets of superconducting qubits are reduced. There may be more and/or greater differences between them. In various cases, these more and/or larger differences in structural properties, even when affected by process variations, cause the structural properties of the unique sets of superconducting qubits to target-based frequency collisions. It can help ensure that they vary sufficiently to reduce the likelihood of

[0027] In other words, if we generate sets of 5 unique superconducting qubits from a fixed pool of possible qubit structural characteristics, these 5 unique sets are less than or equal to and/or can have smaller structural differences, which can be more easily obscured by inherent and/or unintended process changes during nanofabrication and/or microfabrication. is blurred, thereby increasing the likelihood of target-based frequency collisions. On the other hand, if you create three unique sets of superconducting qubits from a fixed pool of possible qubit structural properties, these three unique sets may have more and/or larger structural differences (e.g. , compared to the situation where sets of at least five unique qubits are fabricated), these more and/or larger structural differences may be due to inherent and/or unintended process changes during nanofabrication and/or microfabrication. It can be less easily obscured, thereby reducing the likelihood of target-based frequency collisions. Thus, by reducing the number of unique sets of superconducting qubits that must be fabricated, the statistical probability of target-based frequency collisions can be reduced.

[0028] Since various embodiments of the present invention may facilitate the creation of a quantum computing lattice using sets of three unique superconducting qubits rather than sets of five unique superconducting qubits, the various embodiments of the present invention Embodiments may reduce the probability and/or prevalence of target-based frequency collisions. Moreover, in various cases, a reduction in the probability and/or spread of such target-based frequency collisions may be achieved without a corresponding reduction in grid connectivity. For at least these reasons, various embodiments of the present invention achieve specific and tangible technological improvements in the field of superconducting qubit fabrication. Moreover, in various cases, reduction in the probability and/or spread of these target-based frequency collisions may be achieved without the use of magnetic fluxes (e.g., in various embodiments, an embodiment of the present invention). may provide physical lattice structures that are less susceptible to target-based frequency collisions, do not exhibit reduced connectivity, and do not require the use of magnetic flux to facilitate selective cross-resonant entanglement).

[0029] In various embodiments, one or more of these technological advantages is a quantum computing lattice based on a double-junction transmon qubit coupled with mode-selective couplers (e.g., a pair of This can be facilitated by creating architectures/structures that can facilitate mode-selective coupling between superconducting qubits. In various embodiments, the control qubit can be a double-junction transmon qubit. That is, in various cases, the control qubit can include a first Josephson junction and a second Josephson junction, where the first Josephson junction is coupled in series between an end capacitor pad and a middle capacitor pad, and a second Josephson junction. is coupled in series between the middle capacitor pad and the other end capacitor. Thus, in various cases, the control qubit may have two unique transition frequencies: a first A-mode transition frequency and a first B-mode transition frequency. In various embodiments, a control qubit can be coupled to a target qubit. In various cases, the target qubit can also be a double-junction transmon qubit (eg, with two Josephson junctions, two end capacitor pads and one middle capacitor pad). Thus, in various cases, the target qubit may have two unique transition frequencies: a second A-mode transition frequency and a second B-mode transition frequency.

[0030] In various cases, the control qubit may be coupled to the target qubit by a first mode-selective coupler. In various embodiments, the first mode-selective coupler may facilitate A-mode coupling between the control qubit and the target qubit (e.g., when coupled via the first mode-selective coupler, the control qubit The A-mode of the qubit can couple and/or entangle the A-mode of the target qubit, but the B-mode of the control qubit cannot couple and/or entangle the B-mode of the target qubit). In various cases, to facilitate this A-mode coupling, the first mode-selective coupler may include a capacitor that capacitively couples the middle capacitor pad of the control qubit and the middle capacitor pad of the target qubit. . In various embodiments, the capacitor of the first mode-selective coupler is a control cue, such as a contiguous piece of metal and/or a coplanar waveguide suitably proximal to the middle capacitor pad of the control qubit and the middle capacitor pad of the target qubit. It may be any suitable micro-structure and/or nano-structure that exhibits a net capacitance between the middle capacitor pad of the bit and the middle capacitor pad of the target qubit. In various cases, the capacitance of the capacitor can be less than the shunting capacitance values associated with the control qubit and can be less than the shunting capacitance values associated with the target qubit. In various embodiments, those skilled in the art will be able to understand how to fabricate and/or implement such a capacitor between the middle capacitor pad of the control qubit and the middle capacitor pad of the target qubit. In various embodiments, such a capacitor between the middle capacitor pad of the control qubit and the middle capacitor pad of the target qubit may facilitate A-mode coupling between the control qubit and the target qubit and/or the control qubit. B-mode coupling between β and the target qubit can be prevented.

[0031] In various other cases, the control qubit may be coupled to the target qubit by the second mode-selective coupler rather than the first mode-selective coupler. In various embodiments, the second mode-selective coupler can facilitate B-mode coupling between the control qubit and the target qubit (e.g., when coupled via the second mode-selective coupler, the control qubit A qubit's B-mode can couple and/or entangle the target qubit's B-mode, but the control qubit's A-mode cannot couple and/or entangle the target qubit's A-mode). In various cases, to facilitate this B-mode coupling, the second mode-selective coupler may include a first capacitor and a second capacitor. In various cases, the first capacitor can capacitively couple the end capacitor pad of the control qubit to the end capacitor pad of the target qubit. In various cases, the second capacitor can capacitively couple the end capacitor pad of the control qubit to the middle capacitor pad of the target qubit. In various embodiments, the first capacitor of the second mode-selective coupler is a control qubit, such as a contiguous piece of metal and/or a coplanar waveguide suitably proximate to the end capacitor pad of the control qubit and the end capacitor pad of the target qubit. It may be any suitable microstructure and/or nanostructure that exhibits a net capacitance between the qubit's end capacitor pad and the target qubit's end capacitor pad. Similarly, in various embodiments, the second capacitor of the second mode-selective coupler is a series of metal and/or coplanar waveguides suitably proximal to the end capacitor pad of the control qubit and the middle capacitor pad of the target qubit. It may be any suitable microstructure and/or nanostructure that exhibits a net capacitance between the end capacitor pad of the control qubit, such as a piece, and the middle capacitor pad of the target qubit. In various cases, the first capacitance of the first capacitor can be less than the shunting capacitance values associated with the control qubit and can be less than the shunting capacitance values associated with the target qubit. In various cases, the second capacitance of the second capacitor may be half the first capacitance. In various embodiments, those skilled in the art will be able to understand how to fabricate and/or implement a first capacitor between the end capacitor pad of the control qubit and the end capacitor pad of the target qubit, and also between the end capacitor pad of the control qubit and It will be appreciated how to fabricate and/or implement the second capacitor between the middle capacitor pads of the target qubit. In various embodiments, this first capacitor between the end capacitor pad of the control qubit and the end capacitor pad of the target qubit and this second capacitor between the end capacitor pad of the control qubit and the middle capacitor pad of the target qubit It may facilitate B-mode coupling between the control qubit and the target qubit and/or prevent A-mode coupling between the control qubit and the target qubit.

[0032] In various other embodiments, the control qubit may be coupled to a first target qubit and a second target qubit, both of which may be double-junction transmon qubits (e.g., the control qubit). A qubit may have two Josephson junctions, two end capacitor pads and a middle capacitor pad; the first target qubit may have two Josephson junctions, two end capacitor pads and a middle capacitor pad. may have; the second target qubit may have two Josephson junctions, two end capacitor pads and one middle capacitor pad). Thus, the first target qubit has two distinct transition frequencies, e.g., an A-mode transition frequency (denoted f _A1 , where f _A1 can be any suitable frequency value) and a B-mode transition frequency (denoted f _B1 ). , where f _B1 is not equal to f _A1 ). Similarly, the second target qubit has two unique transition frequencies, e.g., an A-mode transition frequency (denoted as f _A2 , where f _A2 can be any suitable frequency value) and a B-mode transition frequency (denoted as f _B2 ; where f _B2 is not equal to f _A2 In various cases, the control qubit is a first mode-selective coupler (e.g., the middle capacitor pad of the control qubit is connected to the first, as described above). a capacitor coupled to a middle capacitor pad of the target qubit) to facilitate A-mode coupling between the control qubit and the first target qubit, thereby facilitating A-mode coupling between the control qubit and the first target qubit. Prevents B-mode coupling between the first target qubit In various cases, the control qubit is a second mode-selective coupler (e.g., connecting the end capacitor pad of the control qubit to the second target qubit), as described above. a first capacitor coupling the end capacitor pad of a bit and a second capacitor coupling the same end capacitor pad of a control qubit to a middle capacitor pad of a second target qubit; This prevents A-mode coupling between the control qubit and the second target qubit by facilitating B-mode coupling between the control qubit and the second target qubit.

[0033] In various examples, the first target qubit and the second target qubit can be non-degenerate targets. That is, in some cases, the first target qubit and the second target qubit may have different structural properties, such that f _A1 may not be equal to f _A2 and f _B1 may not be equal to f _B2 . In such a case, selective cross-resonant entanglement between the control qubit and the first target qubit and/or the second target qubit may be facilitated. Specifically, in some cases, the control qubit can be driven by a microwave pulse and/or tone with a frequency of f _A1 . In such case, the control qubit may be entangled with the first target qubit (e.g., the microwave pulse and/or tone has a frequency matching the A-mode transition frequency of the first target qubit, and the first mode-selective The coupler can facilitate A-mode coupling between the control qubit and the first target qubit, thereby causing entanglement). However, in such a case, the control qubit can avoid becoming entangled with the second target _qubit (e.g., since the targets are nondegenerate , a microwave pulse and/or tone with a frequency of does not match either the A-mode transition frequency ( f _A2 ) or the B-mode transition frequency ( f _AB2 ) of the qubit, thereby preventing entanglement). In some cases, the control qubit can be driven by a microwave pulse and/or tone with a frequency of f _B2 . In such case, the control qubit may be entangled with the second target qubit (e.g., the microwave pulse and/or tone has a frequency matching the B-mode transition frequency of the second target qubit, and the second mode-selective The coupler may facilitate B-mode coupling between the control qubit and the second target qubit, thereby causing entanglement). Moreover, in such a case, the control qubit can avoid becoming entangled with the first target _qubit (e.g., since the targets are nondegenerate , a microwave pulse and/or tone with a frequency of does not match the qubit's A-mode transition frequency ( f _A1 ) or B-mode transition frequency ( f _B1 )). It should be noted that in various embodiments, a microwave pulse and/or tone with a frequency of f _B1 may, in some cases, not cause the control qubit to become entangled with either the first target qubit or the second target qubit. (e.g., the frequency of the microwave pulses and/or tones does not match the A-mode transition frequency or the B-mode transition frequency of the second target qubit; the frequency of the microwave pulses and/or tones does not match the frequency of the first target qubit The first mode-selective coupler may prevent B-mode coupling between the control qubit and the first target qubit even if it matches the B-mode transition frequency of the bit). Similarly, note that, in various embodiments, a microwave pulse and/or tone having a frequency of f _A2 may in some cases cause the control qubit to become entangled with either the first target qubit or the second target qubit. (e.g., the frequency of the microwave pulses and/or tones does not match the A-mode transition frequency or B-mode transition frequency of the first target qubit; the frequency of the microwave pulses and/or tones does not match the second target qubit's frequency) Even if it matches the A-mode transition frequency of the target qubit, the second mode-selective coupler may prevent A-mode coupling between the control qubit and the second target qubit).

[0034] In various examples, the first target qubit and the second target qubit can be degenerate targets. That is, in some cases, the first target qubit and the second target qubit are similar such that f _A1 is equal to and/or substantially equal to f _A2 and f _B1 is equal to and/or substantially equal to f _B2 . and/or may have the same structural properties. Even in such a case, selective entanglement between the control qubit and the first target qubit and/or the second target qubit can be facilitated. Specifically, in some cases, the control qubit can be driven by a microwave pulse and/or tone with a frequency of f _A1 =f _A2 . In such a case, the control qubit may become entangled with the first target qubit but not with the second target qubit. Consequently, the microwave pulses and/or tones have a frequency that matches the A-mode transition frequency of the first target qubit, and the first mode-selective coupler establishes A-mode coupling between the control qubit and the first target qubit. can be done easily While the microwave pulse and/or tone has a frequency that also coincides with the A-mode transition frequency of the second target qubit (e.g. because they are degenerate targets), the second mode-selective coupler is coupled with the control qubit and the second target qubit. A-mode coupling between them can be prevented. In some cases, the control qubit can be driven by a microwave pulse and/or tone with a frequency of f _B1 =f _B2 . In such a case, the control qubit may be entangled with the second target qubit but not with the first target qubit. Consequently, the microwave pulses and/or tones have a frequency that matches the B-mode transition frequency of the second target qubit, and the second mode-selective coupler establishes B-mode coupling between the control qubit and the second target qubit. can be done easily The microwave pulse and/or tone has a frequency that also coincides with the B-mode transition frequency of the first target qubit (e.g. because they are degenerate targets), but the first mode-selective coupler has a control qubit and a first target qubit. B-mode coupling between them can be prevented.

[0035] Thus, even in the presence of degenerate targets, embodiments of the present invention can facilitate selective cross-resonant entanglement. As a stark contrast, degenerate targets in a quantum computing lattice employing single-junction transmon qubits coupled with bus resonators may not undergo selective cross-resonant entanglement.

[0036] In various embodiments, the control qubit can be further coupled to the third target qubit and the fourth target qubit. In various cases, the third target qubit and the fourth target qubit may be a double-junction transmon qubit (e.g., the third target qubit has two Josephson junctions, two end capacitor pads and a middle capacitor pads; the fourth target qubit can have two Josephson junctions, two end capacitor pads and one middle capacitor pad). In various embodiments, the third target qubit and the fourth target qubit may be degenerate targets (eg, may be similar and/or identical to each other), and the first target qubit and the second target qubit may be degenerate targets. It can be non-degenerate with 2 target qubits. In various embodiments, another example of the first mode-selective coupler may couple a control qubit to a third target qubit, and another example of the second mode-selective coupler may couple a control qubit to a fourth target qubit. can be attached to bits. Thus, in various cases, A-mode coupling may be facilitated between the control qubit and the third target qubit, and B-mode coupling may be facilitated between the control qubit and the fourth target qubit. In various embodiments, selective cross-resonant entanglement between the control qubit and the third target qubit and/or the fourth target qubit is facilitated, as described above for the first and second target qubits. It can be.

[0037] That is, in various embodiments, the control qubit can be coupled to four target qubits (eg, first, second, third, and fourth target qubits), in this way the control qubit and two target qubits (eg, first and third target qubits), A-mode coupling may be easy, and the control qubit and two other target qubits (eg, second and third target qubits) 4 target qubits) can facilitate B-mode coupling. With such a configuration, selective cross-resonant entanglement between the control qubit and one of the four target qubits can be facilitated, despite the fact that the first and second target qubits are degenerate and the third and second Despite the fact that 4 target qubits are degenerate, it can be easily done. Since there could be two pairs of degenerate targets in such a scenario, there could be 3 unique sets of superconducting qubits in the quantum computing lattice, rather than 5 unique sets of superconducting qubits (e.g., the control queue a set corresponding to the bit, a set corresponding to the first and second target qubits to be degenerated, and a set corresponding to the third and fourth target qubits to be degenerate). In various embodiments, this reduction in the number of unique sets of superconducting qubits needed to form a quantum computing lattice reduces the probability and/or spread of target-based frequency collisions without correspondingly reducing lattice connectivity. can make it Accordingly, various embodiments of the present invention achieve specific and tangible technological improvements in the field of superconducting qubit fabrication.

[0038] To clarify the discussion above, consider the following non-limiting example. Consider a control qubit and four target qubits W, X, Y and Z. Assume that the control qubit and the four target qubits W, X, Y and Z are double-junction transmon qubits. Also, assume that target qubit W and target qubit X are degenerate, and target qubit Y and target qubit Z are degenerate. In that case, only three types and/or sets of qubits are included in the example: the first type and/or set corresponding to the control qubit, and corresponding to the degenerate target qubits W and X. and a third type and/or set corresponding to the degenerate target qubits Y and Z. Assume that the control qubit is coupled to the target qubit W by a mode-selective coupler facilitating A-mode coupling, and the control qubit is coupled to the target qubit X by a mode-selective coupler facilitating B-mode coupling. is assumed to be coupled to Similarly, suppose the control qubit is coupled to the target qubit Y by a mode-selective coupler facilitating A-mode coupling, and the control qubit is coupled to the target qubit by a mode-selective coupler facilitating B-mode coupling. Assume that it is coupled to qubit Z.

[0039] In various embodiments, selective cross-resonant entanglement may be facilitated. In some cases, the control qubit may be driven by a microwave pulse and/or tone with a frequency corresponding to the A-mode transition frequency of the target qubit W. Because the frequency of the microwave pulses and/or tones matches the A-mode transition frequency of the target qubit W, and because A-mode coupling between the control qubit and the target qubit W is facile, the control qubit is the target qubit. can be entangled with W. It should be noted that in such a case, the control qubit can avoid being entangled with the target qubit X. Consequently, even if the microwave pulse and/or tone has a frequency that matches the A-mode transition frequency of the target qubit X (e.g. W and X are degenerate targets), there is an A-mode transition between the control qubit and the target qubit X. Mode coupling is not easy, instead only B-mode coupling between the control qubit and the target qubit X is facilitated. Also, the control qubit can avoid entanglement with the target qubits Y and Z in such a case, since the A-mode transition frequency and the B-mode transition frequency do not match the frequencies of the microwave pulses and/or tones (e.g. For example: Y and Z can be non-degenerate to W and X).

[0040] In various cases, the control qubit may be driven by a microwave pulse and/or tone having a frequency corresponding to the B-mode transition frequency of the target qubit X. The control qubit becomes entangled with the target qubit X because the frequency of the microwave pulses and/or tones coincides with the B-mode transition frequency of the target qubit X and B-mode coupling between the control qubit and the target qubit X is facile. can It should be noted that in such a case the control qubit can avoid being entangled with the target qubit W. After all, even if the microwave pulse and/or tone has a frequency that matches the B-mode transition frequency of the target qubit W (e.g., W and X are degenerate targets), between the control qubit and the target qubit W B-mode coupling of is not easy, instead only A-mode coupling between the control qubit and the target qubit W is facilitated. It should also be noted that the control qubit avoids entanglement with the target qubits Y and Z in such a case because the A-mode transition frequency and the B-mode transition frequency do not match the frequencies of the microwave pulses and/or tones (e.g. For example, Y and Z can be nondegenerate into W and X).

[0041] In various cases, the control qubit may be driven by a microwave pulse and/or tone having a frequency corresponding to the A-mode transition frequency of the target qubit Y. Because the frequency of the microwave pulses and/or tones coincides with the A-mode transition frequency of the target qubit Y, and A-mode coupling between the control qubit and the target qubit Y is facile, the control qubit is coupled with the target qubit Y. can get tangled It should be noted that in such a case the control qubit can avoid being entangled with the target qubit Z. Consequently, even if the microwave pulse and/or tone has a frequency that matches the frequency of the A-mode transition of the target qubit Z (e.g., Y and Z are degenerate targets), there is a gap between the control qubit and the target qubit Z. A-mode coupling is not easy, instead only B-mode coupling between the control qubit and the target qubit Z is facilitated. It should also be noted that the control qubit avoids entanglement with the target qubits W and X in such a case, since the A-mode transition frequency and B-mode transition frequency do not match the frequencies of the microwave pulses and/or tones (e.g. For example, W and X can be nondegenerate into Y and Z).

[0042] In various cases, the control qubit may be driven by a microwave pulse and/or tone having a frequency corresponding to the B-mode transition frequency of the target qubit Z. Because the frequency of the microwave pulses and/or tones coincides with the B-mode transition frequency of the target qubit Z, and B-mode coupling between the control qubit and the target qubit Z is facile, the control qubit is coupled to the target qubit Z and can get tangled It should be noted that in such a case the control qubit can avoid being entangled with the target qubit Y. Consequently, even if the microwave pulse and/or tone has a frequency that matches the B-mode transition frequency of the target qubit Y (e.g., Y and Z are degenerate targets), there is a gap between the control qubit and the target qubit Y. B-mode coupling is not easy, instead only A-mode coupling between the control qubit and the target qubit Y is facilitated. It should also be noted that the control qubit avoids entanglement with the target qubits W and X in such a case, since the A-mode transition frequency and B-mode transition frequency do not match the frequencies of the microwave pulses and/or tones (e.g. For example, W and X can be nondegenerate into Y and Z).

[0043] As shown by this non-limiting example, various embodiments of the present invention do not require sets of up to 5 or so unique superconducting qubits, but as few as 3 or so unique superconducting qubits. Sets of bits may facilitate selective cross-resonant entanglement. A reduction in the number of unique sets of superconducting qubits needed to facilitate selective cross-resonant entanglement can in many cases reduce the statistical probability of target-based frequency collisions without reducing lattice connectivity.

[0044] The various embodiments of the present invention are mode-selective coupling for frequency collision reduction that is neither abstract, nor natural phenomenon, nor law of nature, and cannot be performed as a series of mental actions by humans. including new systems, architectures and/or technologies to facilitate Instead, various embodiments of the present invention include systems, architectures, and/or techniques to facilitate frequency collision reduction without requiring a corresponding reduction in grid connectivity. Frequency conflicts can negatively impact the performance of a quantum computing grid. Some techniques can reduce the likelihood of frequency collisions by reducing lattice connectivity (eg, by reducing the number of connections in a quantum computing lattice), but such low-degree lattices are more susceptible to errors. Various embodiments of the present invention can reduce the statistical probability of frequency collisions without reducing grid connectivity. Specifically, the control qubit can be coupled to the first target qubit by a first mode-selective coupler that can facilitate A-mode coupling between the control qubit and the first target qubit (e.g., A suitable structure of such a first mode-selective coupler is disclosed herein). Similarly, the control qubit can be coupled to the second target qubit by a second mode-selective coupler that can facilitate B-mode coupling between the control qubit and the second target qubit (e.g., A suitable structure of such a second mode-selective coupler is disclosed herein). In various embodiments, the first and second mode-selective couplers may allow selective cross-resonant entanglement to occur even when the first and second target qubits are degenerate. In a nearest-neighbor-connected quantum computing lattice composed of double-junction transmon qubits (e.g., where each non-perimetral qubit is coupled to all four of its adjacent neighbors), such a The first and second mode-selective couplers may allow selective cross-resonance entanglement to occur with sets of three unique superconducting qubits. That is, various embodiments of the present invention may reduce the number of unique sets of qubits required to implement selective cross-resonant entanglement in a nearest-neighbor-connected quantum computing lattice. This reduction in the number of sets of unique qubits can correspondingly reduce the likelihood of frequency collisions occurring within the quantum computing lattice. Accordingly, various embodiments of the present invention can improve the performance of quantum computing systems (eg, reduced probability of target-based frequency collisions), and thus various embodiments of the present invention have specific applications in the field of superconducting qubit fabrication. and achieve tangible technical improvements.

[0045] In various embodiments, it should be understood that the drawings of the present disclosure are illustrative and non-limiting only and are not necessarily drawn to scale.

[0046] FIG. 1 shows a circuit diagram of an exemplary non-limiting system 100 that may facilitate A-mode coupling in accordance with one or more embodiments described herein. As shown, system 100 may include a double-junction transmon qubit 102 and a double-junction transmon qubit 104 .

[0047] In various embodiments, the double-junction transmon qubit 102 may include a Josephson junction 106 shunted by a capacitor 110. In various embodiments, the double-junction transmon qubit 102 may also include a Josephson junction 108 shunted by a capacitor 112 . In various embodiments, the double-junction transmon qubit 102 may further include a capacitor 114 that shunts both the Josephson junction 106 and the Josephson junction 108 . In various embodiments, the double-junction transmon qubit 102 may be considered to include two single-junction transmon qubits coupled in series to share a capacitor pad. Specifically, Josephson junction 106 shunted by capacitor 110 can be considered a first single-junction transmon qubit formed from a first capacitor pad and a second capacitor pad (not shown in FIG. 1 ). In various embodiments, the first capacitor pad and the second capacitor pad may shunt Josephson junction 106 to form capacitor 110 . Josephson junction 108 shunted by capacitor 112 can also be considered a second single-junction transmon qubit formed from the second and third capacitor pads (not shown in FIG. 1). In various embodiments, the second capacitor pad and the third capacitor pad may shunt Josephson junction 108 to form capacitor 112 . Additionally, the first capacitor pad and the third capacitor pad may shunt both Josephson junction 106 and Josephson junction 108 to form capacitor 114 . In various embodiments, the physical structure of the double-junction transmon qubit 102 may be depicted more clearly in FIG. 2 discussed below.

[0048] In various examples, the double-junction transmon qubit 102 may support and/or exhibit two distinct excitation modes. In various embodiments, these two unique modes of excitation may be referred to as A-mode and B-mode. In various embodiments, the A-mode may be associated with the A-mode transition frequency of the double-junction transmon qubit 102 . Similarly, the B-mode may be associated with the B-mode transition frequency of the double-junction transmon qubit 102 . In various embodiments, the A-mode transition frequency may be distinct and/or not identical to the B-mode transition frequency. As will be appreciated by those skilled in the art, the A-mode transition frequency and/or B-mode transition frequency of the double-junction transmon qubit 102 is set during fabrication, depending on inherent and/or unintended process changes. can be and/or controlled.

[0049] In some embodiments, the double-junction transmon qubit 102 may be encoded in A-mode and/or B-mode. In various embodiments, when the double-junction transmon qubit 102 is encoded in A-mode, the double-junction transmon qubit can represent an A-mode transition frequency and represents a B-mode transition frequency. can avoid In various embodiments, when the double-junction transmon qubit 102 is encoded in B-mode, the double-junction transmon qubit 102 may exhibit a B-mode transition frequency and an A-mode It is possible to avoid representing transition frequencies.

[0050] In various embodiments, the double-junction transmon qubit 102 may be encoded in A-mode and/or B-mode by short microwave pulses, as will be understood by those skilled in the art. (eg, the double-junction transmon qubit 102 can be switched from A-mode to B-mode and/or from B-mode to A-mode).

[0051] In various embodiments, the double-junction transmon qubit 104 may be similar to the double-junction transmon qubit 102. That is, in various embodiments, the double-junction transmon qubit 104 may include a Josephson junction 116 shunted by a capacitor 120 . In various cases, the double-junction transmon qubit 104 may also include a Josephson junction 118 shunted by a capacitor 122 . In various cases, the double-junction transmon qubit 104 may further include a capacitor 124 that shunts both Josephson junction 116 and Josephson junction 118 . In various embodiments, the double-junction transmon qubit 104 may be considered to include two single-junction transmon qubits coupled in series to share a capacitor pad. Specifically, the Josephson junction 116 shunted by the capacitor 120 is separate from the first and second capacitor pads of the double-junction transmon qubit 102 and the second capacitor pad. , not shown in FIG. 1) can be considered as a first single-junction transmon qubit formed. In various embodiments, the first capacitor pad and the second capacitor pad may shunt Josephson junction 116 to form capacitor 120 . Also, the Josephson junction 118 shunted by the capacitor 122 is separate from the second and third capacitor pads of the second and third capacitor pads of the double-junction transmon qubit 102; (not shown in Figure 1) can be considered as a second single-junction transmon qubit formed from In various embodiments, the second capacitor pad and the third capacitor pad may shunt Josephson junction 118 to form capacitor 122 . Additionally, the first capacitor pad and the third capacitor pad may shunt both Josephson junction 116 and Josephson junction 118 to form capacitor 124 . In various embodiments, the physical structure of the double-junction transmon qubit 104 may be more clearly depicted in FIG. 2 discussed below.

[0052] In various examples, the bi-junction transmon qubit 104 may support and/or exhibit two unique modes of excitation. In various embodiments, these two unique modes of excitation may be referred to as A-mode and B-mode. In various embodiments, the A-mode may be associated with the A-mode transition frequency of the double-junction transmon qubit 104 . Similarly, the B-mode may be associated with the B-mode transition frequency of the double-junction transmon qubit 104 . In various embodiments, the A-mode transition frequency may be unique and/or unequal to the B-mode transition frequency. In various embodiments, the A-mode transition frequency and the B-mode transition frequency of the double-junction transmon qubit 104 are the A-mode transition frequency and the B-mode transition frequency of the double-junction transmon qubit 102, respectively. It may be different and/or not the same as the mode transition frequency.

[0053] Similar to double-junction transmon qubit 102, in some embodiments, double-junction transmon qubit 104 may also be encoded in A-mode and/or B-mode. . In various cases, a short wave microwave pulse can be used to switch between A-mode encoding and B-mode encoding, as will be appreciated by those skilled in the art. As will be appreciated by those skilled in the art, the A-mode transition frequency and/or B-mode transition frequency of the double-junction transmon qubit 104 may be manufactured according to inherent and/or unintended process changes. can be set and/or controlled during

[0054] In various embodiments, the double-junction transmon qubit 102 may be coupled to the double-junction transmon qubit 104 by a first mode-selective coupler 126. In various embodiments, the first mode-selective coupler 126 may facilitate A-mode coupling between the double-junction transmon qubit 102 and the double-junction transmon qubit 104. there is. In other words, the first mode-selective coupler 126 causes the A-mode excitation of the double-junction transmon qubit 102 to be different from the A-mode excitation of the double-junction transmon qubit 104. can function to couple and/or to be entangled, and the B-mode excitation of the double-junction transmon qubit 102 will couple with the B-mode excitation of the double-junction transmon qubit 104 and/or may function to be unentangled. In various embodiments, as shown, first mode-selective coupler 126 may include capacitor 128 . In various embodiments, the capacitor 128 connects the middle capacitor pad (eg, the second capacitor pad) of the double-junction transmon qubit 102 to the middle capacitor pad (eg, the second capacitor pad) of the double-junction transmon qubit 104. eg a second capacitor pad). In various embodiments, the capacitance of capacitor 128 may be less than shunting capacitance values of double-junction transmon qubit 102 (e.g., less than the capacitance of capacitor 110, , may be less than the capacitance of the capacitor 112, may be less than the capacitance of the capacitor 114), may be less than the value of the shunting capacitance of the double-junction transmon qubit 104 (e.g., the capacitor ( 120), may be less than the capacitance of the capacitor 122, and may be less than the capacitance of the capacitor 124). In various embodiments, such a capacitive coupling structure facilitates A-mode coupling between the double-junction transmon qubit 102 and the double-junction transmon qubit 104, while the double-junction B-mode coupling between the transmon qubit 102 and the double-junction transmon qubit 104 can be prevented. In various examples, the structure of first mode-selective coupler 126 may be shown more clearly than in FIG. 2 discussed below.

[0055] In various embodiments, the double-junction transmon qubit 102 can function as a control qubit and the double-junction transmon qubit 104 can function as a target qubit. In various embodiments, a cross-resonance direction is the first mode-selective coupler 126 from the double-junction transmon qubit 102 to the double-junction transmon qubit 104. It is said to run along.

[0056] FIG. 2 shows a block diagram of an example non-limiting system 200 that may facilitate A-mode coupling in accordance with one or more embodiments described herein. In various embodiments, FIG. 2 may describe a physical structure/architecture that may implement the circuit shown in 1 .

[0057] In various embodiments, the system 200 includes a double-junction transmon qubit 102 and a double-junction transmon qubit (which may be coupled together by a first mode-selective coupler 126). 104) may be included. As described above, FIG. 1 shows circuit diagrams of the double-junction transmon qubit 102 and the double-junction transmon qubit 104 and the first mode-selective coupler 126 . On the other hand, FIG. 2 shows a physical structure and/or data that can be used to implement the double-junction transmon qubit 102 and the double-junction transmon qubit 104 and the first mode-selective coupler 126. shows the architecture.

[0058] In various embodiments, the double-junction transmon qubit 102 is a Josephson junction 106, a Josephson junction 108, an end capacitor pad 202, an end capacitor pad 204 and a middle capacitor pad. (206). As shown, in various embodiments, end capacitor pad 202 may be coupled to Josephson junction 106 . Similarly, as shown, middle capacitor pad 206 can be coupled to Josephson junction 106 such that end capacitor pad 202, Josephson junction 106 and middle capacitor pad 206 are in series with each other. In various embodiments, end capacitor pad 202 and middle capacitor pad 206 may be considered shunting Josephson junction 106 . That is, the end capacitor pad 202 and the middle capacitor pad 206 may jointly form and/or function as the capacitor 110 in various embodiments.

As shown, in various embodiments, Josephson junction 108 may be coupled to middle capacitor pad 206 . Similarly, as shown, end capacitor pad 204 can be coupled to Josephson junction 108 such that middle capacitor pad 206, Josephson junction 108 and end capacitor pad 204 are in series with each other. In various embodiments, middle capacitor pad 206 and end capacitor pad 204 may be considered shunting Josephson junction 108 . That is, the middle capacitor pad 206 and the end capacitor pad 204 may jointly form and/or function as the capacitor 112 in various embodiments.

[0060] As shown, in various embodiments, end capacitor pad 202, Josephson junction 106, middle capacitor pad 206, Josephson junction 108, and end capacitor pad 204 are all in series with each other. can be joined together so that In various cases, end capacitor pad 202 and end capacitor pad 204 may be considered to shunt both Josephson junction 106 and Josephson junction 108 . That is, the end capacitor pad 202 and the end capacitor pad 204 may jointly form and/or function as the capacitor 114 in various embodiments.

[0061] In various embodiments, as described above, the double-junction transmon qubit 102 may be considered as two series-coupled single-junction transmon qubits that share a middle capacitor pad. Specifically, end capacitor pad 202, Josephson junction 106, and middle capacitor pad 206 can be considered as a first single-junction transmon qubit. Similarly, middle capacitor pad 206, Josephson junction 108, and end capacitor pad 204 can be considered as a second single-junction transmon qubit in series with the first single-junction transmon qubit. As shown, the first single-junction transmon qubit and the second single-junction transmon qubit may share a middle capacitor pad 206 .

[0062] In various embodiments, end capacitor pad 202, middle capacitor pad 206, and end capacitor pad 204 may be a quantum computing system (eg, any suitable superconducting material such as niobium). can be made of any suitable material for forming the shunting capacitor in 2 shows end capacitor pad 202, middle capacitor pad 206 and end capacitor pad 204 as being constructed of the same material, this is not limiting and is for illustrative purposes only. In various embodiments, the end capacitor pad 202 , the middle capacitor pad 206 , and the end capacitor pad 204 may include different materials. In various embodiments, end capacitor pad 202, middle capacitor pad 206, and end capacitor pad 204 can have any suitable size, shape and/or dimension. 2 shows end capacitor pad 202 and end capacitor pad 204 as being of similar size, shape and/or dimensions, this is not limiting and is for illustrative purposes only. In various embodiments, the end capacitor pad 202 and the end capacitor pad 204 may have different sizes, shapes, and/or dimensions. In various embodiments, middle capacitor pad 206 may exhibit an H-shape as shown. In various embodiments, this H-shape can provide additional surface area for bonding purposes. That is, this H-shape can be used to couple (eg, capacitively coupled, direct coupled and/or otherwise) any other suitable quantum computing components and/or circuitry to the middle capacitor pad 206, in any case. A side surface area of the middle capacitor pad 206 may be increased. In various embodiments, middle capacitor pad 206 can have any other suitable size, shape and/or dimension.

[0063] As mentioned above, in various embodiments, the double-junction transmon qubit 102 exhibits two distinct excitation modes, an A-mode and a B-mode. can In various embodiments, a mode structure of the A-mode excitation is a bright mode component of the end capacitor pad 202, a dark mode component of the middle capacitor pad 206 (dark mode component) and a bright mode component of the end capacitor pad 204. In various embodiments, the mode structure of B-mode excitation is a dark mode component of end capacitor pad 202, a neutral and/or zero mode component of middle capacitor pad 206, an end capacitor pad It can consist of the bright mode component of (204).

[0064] In various embodiments, the double-junction transmon qubit 104 may exhibit a similar structure and/or architecture as the double-junction transmon qubit 102. In various embodiments, the double-junction transmon qubit 104 comprises a Josephson junction 116, a Josephson junction 118, an end capacitor pad 208, an end capacitor pad 210, and a middle capacitor pad 212. can include As shown, in various embodiments, end capacitor pad 208 may be coupled to Josephson junction 116 . Similarly, as shown, middle capacitor pad 212 can be coupled to Josephson junction 116 such that end capacitor pad 208, Josephson junction 116 and middle capacitor pad 212 are in series with each other. In various embodiments, end capacitor pad 208 and middle capacitor pad 212 may be considered to shunt Josephson junction 116 . That is, the end capacitor pad 208 and the middle capacitor pad 212 may jointly form and/or function as the capacitor 120 in various embodiments.

As shown, in various embodiments, Josephson junction 118 may be coupled to middle capacitor pad 212 . Similarly, as shown, end capacitor pad 210 may be coupled to Josephson junction 118 such that middle capacitor pad 212, Josephson junction 118 and end capacitor pad 210 are in series with each other. In various embodiments, middle capacitor pad 212 and end capacitor pad 210 may be considered to shunt Josephson junction 118 . That is, the middle capacitor pad 212 and the end capacitor pad 210 may jointly form and/or function as the capacitor 122 in various embodiments.

[0066] As shown, in various embodiments, end capacitor pad 208, Josephson junction 116, middle capacitor pad 212, Josephson junction 118 and end capacitor pad 210 are all in series with each other. can be combined together. In various cases, end capacitor pad 208 and end capacitor pad 210 may be considered to shunt both Josephson junction 116 and Josephson junction 118 . That is, the end capacitor pad 208 and the end capacitor pad 210 may jointly form and/or function as the capacitor 124 in various embodiments.

[0067] In various embodiments, as noted above, the double-junction transmon qubit 104 may be considered as two series-coupled single-junction transmon qubits that share a middle capacitor pad. Specifically, end capacitor pad 208, Josephson junction 116, and middle capacitor pad 212 may be considered as a first single-junction transmon qubit. Similarly, middle capacitor pad 212, Josephson junction 118 and end capacitor pad 210 can be considered as a second single-junction transmon qubit in series with the first single-junction transmon qubit. As shown, the first single-junction transmon qubit and the second single-junction transmon qubit may share a middle capacitor pad 212 .

[0068] In various embodiments, the size, shape, dimensions and/or material of the end capacitor pad 208, the middle capacitor pad 212, and the end capacitor pad 210 may vary from the end capacitor pad 202, the middle capacitor pad 210. 206, and as described above for the end capacitor pad 204.

[0069] In various examples, the mode structure of the A-mode excitation of the double-junction transmon qubit 104 is described above with respect to the mode structure of the A-mode excitation of the double-junction transmon qubit 102. It can be like a bar. Similarly, in various embodiments, the mode structure of the B-mode excitation of the double-junction transmon qubit 104 is related to the mode structure of the B-mode excitation of the double-junction transmon qubit 102. Thus, it may be as described above.

[0070] In various embodiments, as shown, first mode-selective coupler 126 may include capacitor pad 214, capacitor pad 216 and transmission line 218. . In various embodiments, capacitor pad 214 can be capacitively coupled to middle capacitor pad 206 and capacitor pad 216 can be capacitively coupled to middle capacitor pad 212 . In various embodiments, transmission line 218 may directly couple capacitor pad 214 to capacitor pad 216 . In various cases, capacitor pad 214, capacitor pad 216 and transmission line 218 may collectively represent a net capacitance. That is, capacitor pad 214 , capacitor pad 216 , and transmission line 218 may collectively form and/or function as capacitor 128 in various cases. As mentioned above, the capacitance of capacitor 128 (e.g., the net capacitance of capacitor pad 214, capacitor pad 216, and transmission line 218) is equal to the double-junction transmon qubit 102 may be less than the shunting capacitance values of (e.g., less than the capacitance of capacitor 110, less than the capacitance of capacitor 112, and less than the capacitance of capacitor 114), and -may be less than shunting capacitance values of junction transmon qubit 104 (e.g., less than the capacitance of capacitor 120, less than the capacitance of capacitor 122, and less than the capacitance of capacitor 124) may be less than the capacitance).

[0071] In various embodiments, capacitor pad 214 and capacitor pad 216 may be composed of any suitable material for forming a capacitor and/or capacitive connection in a quantum computing system (eg niobium and any suitable superconducting material). Although capacitor pad 214 and capacitor pad 216 are shown in FIG. 2 as being composed of the same material, this is not limiting and is for illustrative purposes only. In various embodiments, capacitor pad 214 and capacitor pad 216 may include different materials. In various embodiments, capacitor pad 214 and capacitor pad 216 can have any suitable size, shape and/or dimension. 2 shows capacitor pad 214 and capacitor pad 216 as having similar sizes, shapes and/or dimensions, this is not limiting and is for illustrative purposes only. In various embodiments, the capacitor pad 214 and the capacitor pad 216 may have different sizes, shapes and/or dimensions. In various embodiments, transmission line 218 may be composed of any suitable conductive material used in a quantum computing system (eg, any suitable superconducting material such as niobium). Although FIG. 2 shows transmission line 218 as being straight, this is not limiting and is for illustrative purposes only. In various embodiments, transmission line 218 can have any suitable size, shape and/or dimension.

[0072] In various embodiments, the first mode-selective coupler 126 may have a structure and/or architecture different from that shown in FIG. 2 (eg, capacitor pad 214, capacitor pad 216 and transmission line 218 and other components). Specifically, in various embodiments, first mode-selective coupler 126 is any suitable structure that exhibits net capacitance, such as a coplanar waveguide between middle capacitor pad 206 and middle capacitor pad 212; It may be an architectural and/or quantum circuit component. That is, first mode-selective coupler 126 functions as a capacitor between middle capacitor pad 206 and middle capacitor pad 212 and/or otherwise connects middle capacitor pad 206 to middle capacitor pad 212. It can be any suitable structure that capacitively binds to.

[0073] In various embodiments, the net capacitive coupling as described above between the middle capacitor pad 206 and the middle capacitor pad 212 is coupled to the double-junction transmon qubit 102 and the 2 A-mode coupling between the middle-junction transmon qubits 104 can be facilitated. Moreover, in various embodiments, the net capacitive coupling as described above between the middle capacitor pad 206 and the middle capacitor pad 212 is a double-junction transmon qubit 102 and a double-junction transmon queue B-mode coupling between bits 104 can be prevented.

[0074] FIG. 3 shows a circuit diagram of an example non-limiting system 300 that may facilitate B-mode coupling in accordance with one or more embodiments described herein. As shown, system 300 may include a double-junction transmon qubit 102 and a double-junction transmon qubit 104 as described above.

[0075] In various embodiments, the double-junction transmon qubit 102 may be coupled to the double-junction transmon qubit 104 by the second mode-selective coupler 302. In various embodiments, the second mode-selective coupler 302 can facilitate B-mode coupling between the double-junction transmon qubit 102 and the double-junction transmon qubit 104. . That is, the second mode-selective coupler 302 is such that the B-mode excitation of the double-junction transmon qubit 102 couples with the B-mode excitation of the double-junction transmon qubit 104. and/or capable of being entangled, such that A-mode excitation of the double-junction transmon qubit 102 cannot couple with A-mode excitation of the double-junction transmon qubit 104 and/or Alternatively, it may function so as not to be entangled. In various embodiments, as shown, the second mode-selective coupler 302 may include a capacitor 304 and a capacitor 306 . In various embodiments, the capacitor 304 connects the end capacitor pad (eg, the first capacitor pad) of the double-junction transmon qubit 102 to the end capacitor pad (eg, the first capacitor pad) of the double-junction transmon qubit 104. eg: the first capacitor pad). In various embodiments, the capacitor 306 connects an end capacitor pad (eg, a first capacitor pad) of the double-junction transmon qubit 102 to a middle capacitor pad (eg, a first capacitor pad) of the double-junction transmon qubit 104. eg a second capacitor pad). In various embodiments, the capacitance of capacitor 304 may be less than shunting capacitance values of double-junction transmon qubit 102 (e.g., less than the capacitance of capacitor 110, capacitor 112 ), and may be less than the capacitance of capacitor 114), and may be less than the shunting capacitance values of the double-junction transmon qubit 104 (e.g., the capacitance of capacitor 110). may be less than the capacitance, may be less than the capacitance of capacitor 112, and may be less than the capacitance of capacitor 124). In various cases, the capacitance of capacitor 306 may be half the capacitance of capacitor 304 . In various embodiments, such a capacitive coupling structure facilitates B-mode coupling between the double-junction transmon qubit 102 and the double-junction transmon qubit 104 while simultaneously forming a double-junction transmon qubit. A-mode coupling between the mon qubit 102 and the double-junction transmon qubit 104 can be prevented. In various examples, the structure of the second mode-selective coupler 302 may be shown more clearly than in FIG. 4 discussed below.

[0076] In various embodiments, the double-junction transmon qubit 102 can function as a control qubit and the double-junction transmon qubit 104 can function as a target qubit. In various embodiments, the cross-resonance direction can be said to run along the second mode-selective coupler 302 from the double-junction transmon qubit 102 to the double-junction transmon qubit 104. .

[0077] Figure 4 shows a block diagram of an example non-limiting system 400 that may facilitate B-mode coupling in accordance with one or more embodiments described herein. In various embodiments, FIG. 4 may describe a physical structure/architecture that may implement the circuit shown in FIG. 3 .

[0078] In various embodiments, system 400 may include a double-junction transmon qubit 102 and a double-junction transmon qubit 104, as described above, which are in the second mode - can be coupled together by an optional coupler (302). As described above, FIG. 3 shows circuit diagrams of the double-junction transmon qubit 102 , the double-junction transmon qubit 104 and the second mode-selective coupler 302 . On the other hand, FIG. 4 shows a physical structure and/or a physical structure that can be used to implement the double-junction transmon qubit 102, the double-junction transmon qubit 104, and the second mode-selective coupler 302. shows the architecture.

[0079] In various embodiments, as shown, second mode-selective coupler 302 includes capacitor pad 402, capacitor pad 404, capacitor pad 408, transmission line 406 and transmission line (410). In various embodiments, the capacitor pad 402 can be capacitively coupled to the end capacitor pad 202, the capacitor pad 404 can be capacitively coupled to the end capacitor pad 210, and the capacitor pad ( 408) may be capacitively coupled to the middle capacitor pad 212. In various embodiments, transmission line 406 can couple capacitor pad 402 directly with capacitor pad 404 . In various cases, capacitor pad 402, capacitor pad 404, and transmission line 406 may exhibit net capacitance. That is, capacitor pad 402 and capacitor pad 404 and transmission line 406 may collectively form and/or function as capacitor 304 in various instances. As mentioned above, the capacitance of capacitor 304 (e.g., the net capacitance of capacitor pad 402, capacitor pad 404, and transmission line 406) is equal to the shunting of double-junction transmon qubit 102. may be less than the capacitance values (e.g., less than the capacitance of capacitor 110, less than the capacitance of capacitor 112, less than the capacitance of capacitor 114), and a double-junction transformer. may be less than the value of the shunting capacitance of mon qubit 104 (e.g. less than the capacitance of capacitor 120, less than the capacitance of capacitor 122, less than the capacitance of capacitor 124) there is).

[0080] In various embodiments, transmission line 410 may directly couple capacitor pad 402 with capacitor pad 408. In various cases, capacitor pad 402 , capacitor pad 408 and transmission line 410 may exhibit net capacitance. That is, capacitor pad 402 and capacitor pad 408 and transmission line 410 may collectively form and/or function as capacitor 306 in various cases. As noted above, the capacitance of capacitor 306 (e.g., the net capacitance of capacitor pad 402, capacitor pad 408, and transmission line 410) may be half the capacitance of capacitor 304 ( For example, half the net capacitance of capacitor pad 402, capacitor pad 404 and transmission line 406).

[0081] In various embodiments, capacitor pad 402, capacitor pad 404, and capacitor pad 408 may be constructed of any suitable material for forming a capacitor and/or capacitive connection in a quantum computing system ( any suitable superconducting material, for example niobium). Although capacitor pad 402, capacitor pad 404 and capacitor pad 408 are shown in FIG. 4 as being constructed of the same material, this is not limiting and is for illustrative purposes only. In various embodiments, the capacitor pad 402, the capacitor pad 404, and the capacitor pad 408 may include different materials. In various embodiments, capacitor pad 402, capacitor pad 404 and capacitor pad 408 can have any suitable size, shape and/or dimension. Although capacitor pad 402, capacitor pad 404 and capacitor pad 408 are shown in FIG. 4 as having similar sizes, shapes and/or dimensions, this is not limiting and is for illustrative purposes only. In various embodiments, capacitor pad 402 , capacitor pad 404 and capacitor pad 408 may have different sizes, shapes and/or dimensions. In various embodiments, transmission line 406 and transmission line 410 may be constructed of any suitable conductive material used in a quantum computing system (eg, any suitable superconducting material such as niobium). In various embodiments, transmission line 406 and transmission line 410 may include different materials. Although FIG. 4 shows transmission line 406 and transmission line 410 as being straight, this is not limiting and is for illustrative purposes only. In various embodiments, transmission line 406 and transmission line 410 can have any suitable size, shape and/or dimension. Although FIG. 4 shows both transmission line 406 and transmission line 410 coupled to capacitor pad 402, this is not limiting and is for illustrative purposes only. In various cases, capacitor pad 402 may be coupled to transmission line 406 and not coupled to transmission line 410 (eg, in such case, second mode-selective coupler 302 may include a fourth capacitor pad, not shown here, capacitively coupled to the end capacitor pad 202 and coupled directly to the transmission line 410). In various cases, capacitor pad 402 may be coupled to transmission line 410 and not coupled to transmission line 406 (eg, in such case, second mode-selective coupler 302 may include a fourth capacitor pad, not shown here, that is capacitively coupled to the end capacitor pad 202 and directly coupled to the transmission line 406).

[0082] In various embodiments, second mode-selective coupler 302 may have a different structure and/or architecture than that shown in FIG. 4 (eg, capacitor pad 402, capacitor pad 404 ), capacitor pad 408, transmission line 406 and transmission line 410 may have other components). Specifically, in various embodiments, second mode-selective coupler 302 can be any suitable structure, architecture, and structure that exhibits a first net capacitance between end capacitor pad 202 and end capacitor pad 210, such as a coplanar waveguide. /or can be a quantum circuit component. A second net capacitance is shown between the end capacitor pad 202 and the middle capacitor pad 212 like a coplanar waveguide. That is, the second mode-selective coupler 302 functions as a first capacitor between the end capacitor pad 202 and the end capacitor pad 210 and functions as a second capacitor between the end capacitor pad 202 and the middle capacitor pad 212. It may be any suitable structure that functions as a capacitor. That is, the second mode-selective coupler 302 capacitively couples the end capacitor pad 202 to the end capacitor pad 210 and otherwise capacitively couples the end capacitor pad 202 to the middle capacitor pad 212. It can be any suitable structure that combines with.

[0083] In various embodiments, the first net capacitive coupling as described above between the end capacitor pad 202 and the end capacitor pad 210 and the above between the end capacitor pad 202 and the middle capacitor pad 212 A second net capacitive coupling as described above may facilitate B-mode coupling between the double-junction transmon qubit 102 and the double-junction transmon qubit 104 . Moreover, in various embodiments, the first net capacitive coupling as described above between the end capacitor pad 202 and the end capacitor pad 210 and the aforementioned net capacitive coupling between the end capacitor pad 202 and the middle capacitor pad 212 A second net capacitive coupling such as can prevent A-mode coupling between the double-junction transmon qubit 102 and the double-junction transmon qubit 104.

[0084] Although FIG. 4 shows that the second mode-selective coupler 302 can capacitively couple the end capacitor pad 202 to the end capacitor pad 210, this is not intended to be limiting and is for illustrative purposes only. will be. In various embodiments, the second mode-selective coupler 302 connects all end capacitor pads (eg, end capacitor 202 and/or end capacitor pad 204) of the double-junction transmon qubit 102. may be capacitively coupled to all end capacitor pads of the double-junction transmon qubit 104 (eg, end capacitor pad 208 and/or end capacitor pad 210). 4 shows that the second mode-selective coupler 302 can capacitively couple the end capacitor pad 202 to the middle capacitor pad 212, but this is not limiting and is for illustrative purposes only. In various embodiments, the second mode-selective coupler 302 connects all end capacitor pads of the double-junction transmon qubit 102 to the middle capacitor pad 212 of the double-junction transmon qubit 104. , with the proviso that the same end capacitor pad of the double-junction transmon qubit 102 is capacitively coupled to the end capacitor pad of the double-junction transmon qubit 104. do.

[0085] In various embodiments, the double-junction transmon qubit 102 can function as a control qubit and the double-junction transmon qubit 104 can function as a target qubit.

5 shows a block diagram of an example non-limiting system 500 that may facilitate a mode-selective coupler for frequency collision reduction in accordance with one or more embodiments described herein. In various embodiments, FIG. 5 shows that a first mode-selective coupler 126 and a second mode-selective coupler 302 couple a plurality of target qubits together to a control qubit to facilitate selective cross-resonant entanglement. It can show how it can be implemented to do so.

[0087] In various embodiments, system 500 may include a control qubit 502, a first target qubit 504 and a second target qubit 506. In various embodiments, the control qubit 502, the first target qubit 504, and the second target qubit 506 may be double-junction transmon qubits as described above. That is, in various embodiments, the control qubit 502 includes an end capacitor pad 512, a Josephson junction 508, a middle capacitor pad 514, a Josephson junction 510, and an end capacitor pad 516 all coupled in series. ) may be included. Similarly, first target qubit 504 includes end capacitor pad 522, Josephson junction 518, middle capacitor pad 524, Josephson junction 520 and end capacitor pad 526 all coupled in series. can do. Similarly, the second target qubit 506 has an end capacitor pad 532, a Josephson junction 528, a middle capacitor pad 534, a Josephson junction 530, and an end capacitor pad 536 all coupled in series. can include

[0088] As mentioned above, since the first target qubit 504 is a double-junction transmon qubit, it can have both an A-mode transition frequency and a B-mode transition frequency. Similarly, since the second target qubit 506 is a double-junction transmon qubit, it can have both an A-mode transition frequency and a B-mode transition frequency.

[0089] In various cases, the first target qubit 504 and the second target qubit 506 may degenerate. That is, in some cases, the A-mode transition frequency of the first target qubit 504 can be equal to the A-mode transition frequency of the second target qubit 506, and the first target qubit 504 The B-mode transition frequency of may be the same as the B-mode transition frequency of the second target qubit 506 .

As shown, in various embodiments, control qubit 502 may be coupled to first target qubit 504 by first mode-selective coupler 126 . That is, the first mode-selective coupler 126 may capacitively couple the middle capacitor pad 514 to the middle capacitor pad 524 . As also shown, in various embodiments, the control qubit 502 can be coupled to the second target qubit 506 by the second mode-selective coupler 302 . That is, the second mode-selective coupler 302 can capacitively couple the end capacitor pad 516 to the end capacitor pad 532 and capacitively couple the end capacitor pad 516 to the middle capacitor pad 534. can be combined Due to the first mode-selective coupler 126, A-mode coupling can be facilitated between the control qubit 502 and the first target qubit 504, and B-mode coupling can be achieved between the control qubit 502 ) and the first target qubit 504. Similarly, due to the second mode-selective coupler 302, B-mode coupling can be facilitated between the control qubit 502 and the second target qubit 506, and A-mode coupling can be achieved with the control queue between the bit 502 and the second target qubit 506 may be prevented.

[0091] In various embodiments, system 500 facilitates selective cross-resonant entanglement, despite the fact that first target qubit 504 and second target qubit 506 may be degenerate. can do. Specifically, in various cases, control qubit 502 may be driven by a microwave pulse and/or tone having a frequency equal to the A-mode transition frequency of first target qubit 504 . The frequency of the microwave pulses and/or tones is equal to the A-mode transition frequency of the first target qubit 504, and the first mode-selective coupler 126 connects the control qubit 502 and the first target qubit ( 504, the control qubit 502 can be entangled with the first target qubit 504. It should be noted that in such a case, the control qubit 502 can avoid being entangled with the second target qubit 506 . This means that the microwave pulses and/or tones have the same frequency as the A-mode transition frequency of the second target qubit 506 (e.g., the first target qubit 504 and the second target qubit 506 are degenerate), because the second mode-selective coupler 302 can prevent A-mode coupling between the control qubit 502 and the second target qubit 506 .

[0092] In various other cases, control qubit 502 may be driven by a microwave pulse and/or tone having a frequency equal to the B-mode transition frequency of second target qubit 506. The frequency of the microwave pulse and/or tone is equal to the B-mode transition frequency of the second target qubit 506, and the second mode-selective coupler 302 connects the control qubit 502 and the second target qubit ( 506, the control qubit 502 can be entangled with the second target qubit 506. It should be noted that in such a case, the control qubit 502 can avoid being entangled with the first target qubit 504 . This means that the microwave pulses and/or tones have the same frequency as the B-mode transition frequency of the first target qubit 504 (e.g., the first target qubit 504 and the second target qubit 506 do not degeneracy), since the first mode-selective coupler 126 can prevent B-mode coupling between the control qubit 502 and the first target qubit 504 .

[0093] Thus, as described above, the first mode-selective coupler 126 and the second mode-selective coupler 302, even with degenerate targets, to facilitate selective cross-resonance entanglement. , can work together. Moreover, magnetic flux and/or reduced connectivity is not required to facilitate such selective cross-resonant entanglement. As mentioned above, quantum computing lattices employing only single-junction transmon qubits coupled by bus resonators cannot facilitate selective cross-resonant entanglement when degenerate targets are involved. This highlights specific and tangible technical advantages of various embodiments of the present invention.

[0094] FIG. 6 shows a flowchart of an example non-limiting method 600 that may facilitate a mode-selective coupler for frequency collision reduction in accordance with one or more embodiments described herein.

[0095] In various embodiments, act 602 forms a control qubit (eg 502), a first target qubit (eg 504) and a second target qubit (eg 506). wherein the control qubit, the first target qubit and the second target qubit are double-junction transmon qubits. In various embodiments, any suitable micro-machining and/or nano-machining technique may be used to form and/or fabricate the control qubit, the first target qubit and the second target qubit. In various embodiments, the first target qubit and the second target qubit can be degenerated (e.g., the first target qubit and the second target qubit have the same A-mode transition frequency and the same B-mode may have a transition frequency).

[0096] In various embodiments, operation 604 may include capacitively coupling the middle capacitor pad of the control qubit (eg 514) to the middle capacitor pad of the first target qubit (eg 524). , thereby facilitating A-mode coupling between the control qubit and the first target qubit.

[0097] In various cases, operation 606 includes capacitively coupling an end capacitor pad of a control qubit (eg, 516) to an end capacitor pad of a second target qubit (eg, 532), and control capacitively coupling the same end capacitor pad of a qubit to the middle capacitor pad of a second target qubit (e.g., 534), whereby the B-between the control qubit and the second target qubit Facilitates mode coupling.

[0098] In various embodiments, operation 608 applies a first microwave tone to the control qubit that corresponds to an A-mode excitation frequency (eg, an A-mode transition frequency of the first target qubit 504). , thereby entangling the first target qubit with the control qubit.

[0099] In various embodiments, operation 610 applies a second microwave tone to the control qubit that corresponds to a B-mode excitation frequency (eg, a B-mode transition frequency of the second target qubit 506). , thereby entangling the second target qubit with the control qubit.

[00100] Figures 7-8 show graphs of exemplary, non-limiting simulation results of a system that may facilitate mode-selective couplers for frequency collision reduction in accordance with one or more embodiments described herein. do. In various embodiments, FIGS. 7-8 illustrate the selective cross-resonance entanglement behavior of system 500.

[00101] FIG. 7 shows graphs 702 and 704. In various embodiments, graph 702 shows a first signal when control qubit 502 is driven by a microwave pulse and/or a tone whose frequency matches the A-mode transition frequency of first target qubit 504 . An oscillatory behavior (eg, Z-oscillations) of the target qubit 504 may be represented. In various embodiments, graph 704 shows a second pulse when control qubit 502 is driven by a microwave pulse and/or tone having a frequency matching the A-mode transition frequency of first target qubit 504 . It can represent the vibrational response of the target qubit 506 (eg, Z-oscillations).

[00102] As shown in graph 702, first target qubit 504 is a microwave pulse whose control qubit 502 has a frequency matching the A-mode transition frequency of first target qubit 504. and/or experiences Rabi oscillations when driven by a tone. Specifically, the first target qubit 504 is activated when the control qubit 502 is in the 0 state and is driven by a microwave pulse and/or tone that matches the A-mode transition frequency of the first target qubit 504. Vibration response 706 is shown. Additionally, the first target qubit 504 oscillates when the control qubit 502 is in the 1 state and is driven by a microwave pulse and/or tone that matches the A-mode transition frequency of the first target qubit 504. Reaction 708 is shown.

[00103] As shown in graph 704, the second target qubit 506 is a microwave whose frequency the control qubit 502 matches the A-mode transition frequency of the first target qubit 504. It does not experience Rabi vibrations when driven by a pulse and/or tone. Specifically, the second target qubit 506 is activated when the control qubit 502 is in the 0 state and is driven by a microwave pulse and/or tone matching the A-mode transition frequency of the first target qubit 504. Vibration response 710 is shown. Additionally, the second target qubit 506 vibrates when the control qubit 502 is in the 1 state and is driven by a microwave pulse and/or tone that matches the A-mode transition frequency of the first target qubit 504. Reaction 712 is indicated.

[00104] Thus, as shown in graphs 702 and 704, control qubit 502 responds to a microwave pulse and/or tone matching the A-mode transition frequency of first target qubit 504. When driven by , the first target qubit 504 may exhibit Rabi oscillations and the second target qubit 506 may exhibit a non-Rabi oscillatory behavior. That is, the first target qubit 504 can be entangled with the control qubit 502 and the second target qubit 506 can avoid being entangled with the control qubit 502 . In various embodiments, this selective cross-resonant entanglement causes the first mode-selective coupler 126 to couple the control qubit 502 to the first target qubit 504 and the control qubit 502 to the second target qubit. It is caused by the second mode-selective coupler 302 coupling to the qubit 506. Moreover, this selective cross-resonance entanglement may be possible despite the fact that the first target qubit 504 and the second target qubit 506 may be degenerate.

[00105] Figure 8 is similar to Figure 7. 8 shows graphs 802 and 804 . In various embodiments, graph 802 shows a first pulse when control qubit 502 is driven by a microwave pulse and/or tone having a frequency matching the B-mode transition frequency of second target qubit 506 . It can represent the vibrational response of the target qubit 504 (eg, Z-oscillations). In various embodiments, graph 804 shows a second pulse when control qubit 502 is driven by a microwave pulse and/or tone having a frequency matching the B-mode transition frequency of second target qubit 506 . It can represent the vibrational response of the target qubit 506 (eg, Z-oscillations).

[00106] As shown in graph 802, first target qubit 504 is a microwave whose control qubit 502 has a frequency matching the B-mode transition frequency of second target qubit 506. It does not experience Rabi oscillations when driven by a pulse and/or tone. Specifically, the first target qubit 504 is driven by a microwave pulse and/or tone that matches the B-mode transition frequency of the second target qubit 506 when the control qubit 502 is in the 0 state. Vibration response 806 is shown. Additionally, the first target qubit 504 oscillates when the control qubit 502 is in a two-state and is driven by a microwave pulse and/or tone that matches the B-mode transition frequency of the second target qubit 506. Reaction 808 is indicated.

[00107] As shown in graph 804, the second target qubit 506 is a microwave whose frequency the control qubit 502 matches the B-mode transition frequency of the second target qubit 506. It experiences Rabi vibrations when driven by a pulse and/or tone. Specifically, the second target qubit 506 is activated when the control qubit 502 is in the 0 state and is driven by a microwave pulse and/or tone matching the B-mode transition frequency of the second target qubit 506. Vibration response 810 is shown. Additionally, the second target qubit 506 oscillates when the control qubit 502 is in a two-state and is driven by a microwave pulse and/or tone that matches the B-mode transition frequency of the second target qubit 506. Reaction 812 is indicated.

[00108] Thus, as shown in graphs 802 and 804, control qubit 502 responds to a microwave pulse and/or tone matching the B-mode transition frequency of second target qubit 506. When driven by , the second target qubit 506 can exhibit Rabbi vibrations and the first target qubit 504 can exhibit a non-Rabbi vibrational response. That is, the second target qubit 506 can be entangled with the control qubit 502 and the first target qubit 504 can avoid being entangled with the control qubit 502 . In various embodiments, this selective cross-resonance entanglement results in the first mode-selective coupler 126 coupling the control qubit 502 to the first target qubit 504 and the control qubit 502 to the second target qubit. This is caused by the second mode-selective coupler 302 coupling to the qubit 506. Moreover, this selective cross-resonance entanglement can be made possible despite the fact that the first target qubit 504 and the second target qubit 506 can be degenerate.

[00109] FIG. 9 shows a block diagram of an example non-limiting quantum computing grid 900 that may facilitate a mode-selective coupler for frequency collision reduction in accordance with one or more embodiments described herein. . In various embodiments, FIG. 9 illustrates how first mode-selective coupler 126 and second mode-selective coupler 302 can be implemented throughout a quantum computing grid to facilitate selective cross-resonant entanglement. can do.

[00110] In various embodiments, quantum computing grid 900 may include double-junction transmon qubits 902, 904, 906, 908, 910, 912, 914, 916. In various embodiments, the double-junction transmon qubits 902, 904, 906, 908, 910, 912, 914, 916 are double-junction transmon qubits 102 and/or the double-junction transmon qubit 102. It may be configured as described above for the junction transmon qubit 104.

[00111] In various embodiments, as shown, a double-junction transmon qubit 908 is a neighboring qubit, i.e., double-junction transmon qubits 902, 904, 912, 914 ) can be combined. Specifically, the double-junction transmon qubit 908 may be coupled to the double-junction transmon qubit 902 by the second mode-selective coupler 302, and the double-junction transmon qubit 908 Bit 908 may be coupled to a double-junction transmon qubit 904 by a first mode-selective coupler 126, which is a second mode-selective transmon qubit 908. Coupler 302 may couple to a double-junction transmon qubit 914 , and double-junction transmon qubit 908 may be double-junction by a first mode-selective coupler 126 . may be coupled to the transmon qubit 912. Thus, B-mode coupling can be facilitated between the double-junction transmon qubit 908 and the double-junction transmon qubit 902, and A-mode coupling is a double-junction transmon qubit. Can be facilitated between the bit 908 and the double-junction transmon qubit 904, B-mode coupling is between the double-junction transmon qubit 908 and the double-junction transmon qubit ( 914), A-mode coupling can be facilitated between the double-junction transmon qubit 908 and the double-junction transmon qubit 912. Similarly, the double-junction transmon qubit 910 can be coupled to the double-junction transmon qubit 904 by the second mode-selective coupler 302, and the double-junction transmon qubit 904 Bit 910 can be coupled to a double-junction transmon qubit 906 by a first mode-selective coupler 126, which is a second mode-selective transmon qubit 910. The coupler 302 can be coupled to a double-junction transmon qubit 913, and the double-junction transmon qubit 910 can be coupled to a double-junction transmon qubit 910 by a first mode-selective coupler 126. may be coupled to the transmon qubit 914. Thus, B-mode coupling can be facilitated between the double-junction transmon qubit 910 and the double-junction transmon qubit 904, and A-mode coupling is a double-junction transmon qubit. Can be facilitated between the bit 910 and the double-junction transmon qubit 906, B-mode coupling is between the double-junction transmon qubit 910 and the double-junction transmon qubit ( 916), A-mode coupling can be facilitated between the double-junction transmon qubit 910 and the double-junction transmon qubit 914.

[00112] In various embodiments, the double-junction transmon qubit 908 is a control queue having four target qubits, namely the double-junction transmon qubits 902, 904, 912, 914. can be considered as bits. Similarly, in various embodiments, the double-junction transmon qubit 910 is also a control queue with four target qubits, i.e., the double-junction transmon qubits 904, 906, 914, 916. can be considered as bits.

[00113] In various embodiments, the double-junction transmon qubits 902, 904, 906 may degenerate. In various embodiments, double-junction transmon qubits 908 and 910 may also be degenerate. In various embodiments, the double-junction transmon qubits 912, 914, and 916 may also be degenerate. That is, in various cases, quantum computing grid 900 may include three unique sets of superconducting qubits rather than five unique sets. In various embodiments, when first mode-selective coupler 126 and second mode-selective coupler 302 are implemented, such sets of three unique superconducting qubits facilitate selective cross-resonance entanglement. It can be enough.

[00114] Consider the following example. Assume that the double-junction transmon qubit 908 is driven with a microwave tone and/or pulse that matches the A-mode switching frequency of the double-junction transmon qubit 904. In such a case, since the microwave tones and/or pulses match the A-mode transition frequency of the double-junction transmon qubit 904 and the double-junction transmon qubit 908 is the first mode- Since it is coupled to the double-junction transmon qubit 904 by the selectable coupler 126, the double-junction transmon qubit 904 can be entangled with the double-junction transmon qubit 908. . It should be noted that in such a case, the double-junction transmon qubit 902 can avoid being entangled with the double-junction transmon qubit 908. Eventually, the double-junction transmon qubit 908 is coupled to the double-junction transmon qubit 902 by the second mode-selective coupler 302, which is a double-junction transmon qubit ( 908) and the double-junction transmon qubit 902 can prevent A-mode coupling. Moreover, it should be noted that even in such a case, the double-junction transmon qubits 912 and 914 can also avoid becoming entangled with the double-junction transmon qubit 908. As a result, the microwave pulse and/or tone will have a frequency that does not match either the A-mode transition frequency or the B-mode transition frequency of the double-junction transmon qubits 912 and 914 (e.g., double-junction transmon qubits 912 and 914). -junction transmon qubits 912 and 914 may be non-degenerate into double-junction transmon qubits 902 and 904).

[00115] Assume instead that the double-junction transmon qubit 908 is driven with a microwave tone and/or pulse that matches the B-mode transition frequency of the double-junction transmon qubit 902. In that case, since the microwave tones and/or pulses match the B-mode transition frequency of the double-junction transmon qubit 902, and the double-junction transmon qubit 908 Because it is coupled to the double-junction transmon qubit 902 by the selectable coupler 302, the double-junction transmon qubit 902 can be entangled with the double-junction transmon qubit 908. . It should be noted that in such a case, the double-junction transmon qubit 904 can avoid being entangled with the double-junction transmon qubit 908 . Eventually, the double-junction transmon qubit 908 is coupled to the double-junction transmon qubit 904 by the first mode-selective coupler 126, which is a double-junction transmon qubit ( 908) and the double-junction transmon qubit 904 can prevent B-mode coupling. Moreover, it should be noted that in such a case, the double-junction transmon qubits 912 and 914 can also avoid becoming entangled with the double-junction transmon qubit 908. As a result, the microwave pulse and/or tone will have a frequency that does not match either the A-mode transition frequency or the B-mode transition frequency of the double-junction transmon qubits 912 and 914 (e.g., double-junction transmon qubits 912 and 914). -junction transmon qubits 912 and 914 may be non-degenerate into double-junction transmon qubits 902 and 904).

[00116] Assume instead that the double-junction transmon qubit 908 is driven with a microwave tone and/or pulse matching the A-mode transition frequency of the double-junction transmon qubit 912. In that case, since the microwave tones and/or pulses match the A-mode transition frequency of the double-junction transmon qubit 912, and the double-junction transmon qubit 908 Because it is coupled to the double-junction transmon qubit 912 by the selectable coupler 126, the double-junction transmon qubit 912 can be entangled with the double-junction transmon qubit 908. . In such a case, it should be noted that the double-junction transmon qubit 914 can avoid being entangled with the double-junction transmon qubit 908. Eventually, the double-junction transmon qubit 908 is coupled to the double-junction transmon qubit 914 by the second mode-selective coupler 302, which is a double-junction transmon qubit ( 908) and the double-junction transmon qubit 914 to prevent A-mode coupling. Moreover, it should be noted that in such a case, the double-junction transmon qubits 902 and 904 can also avoid becoming entangled with the double-junction transmon qubit 908. As a result, the microwave pulse and/or tone will have a frequency that does not match either the A-mode transition frequency or the B-mode transition frequency of the double-junction transmon qubits 902 and 904 (e.g., -junction transmon qubits 912 and 914 may be non-degenerate into double-junction transmon qubits 902 and 904).

[00117] Assume instead that the double-junction transmon qubit 908 is driven with a microwave tone and/or pulse matching the B-mode transition frequency of the double-junction transmon qubit 914. In that case, since the microwave tones and/or pulses match the B-mode transition frequency of the double-junction transmon qubit 914, and the double-junction transmon qubit 908 Because it is coupled to the double-junction transmon qubit 914 by the selectable coupler 302, the double-junction transmon qubit 914 can be entangled with the double-junction transmon qubit 908. . It should be noted that in such a case the double-junction transmon qubit 912 can avoid being entangled with the double-junction transmon qubit 908 . Eventually, the double-junction transmon qubit 908 is coupled to the double-junction transmon qubit 912 by the first mode-selective coupler 126, which is a double-junction transmon qubit ( 908) and the double-junction transmon qubit 912 can prevent B-mode coupling. Moreover, it should be noted that in such a case, the double-junction transmon qubits 902 and 904 can also avoid becoming entangled with the double-junction transmon qubit 908. As a result, the microwave pulses and/or tones will have a frequency that does not match either the A-mode transition frequency or the B-mode transition frequency of the double-junction transmon qubits 902 and 904 (e.g., the double-junction transmon qubits 902 and 904). Junction transmon qubits 912 and 914 may be non-degenerate into double-junction transmon qubits 902 and 904 .

[00118] Thus, as shown by the non-limiting example above, selective cross-resonant entanglement is a set of three unique superconducting qubits of a superconducting qubit (e.g., a degenerate double-junction trans a first set of mon qubits 902, 904, 906; a second set of degenerate double-junction transmon qubits 908 and 910; and degenerate double-junction transmon qubits ( A third set of 912, 914, 916) may be facilitated in the quantum computing grid 900. Because fewer unique sets of superconducting qubits may be needed to facilitate selective cross-resonance entanglement than the typical five unique sets, various embodiments of the present invention arise from quantum computing lattice 900. can reduce the statistical probability of a target-based frequency collision.

[00119] In various embodiments, quantum computing grid 900 may include any suitable number of superconducting qubits and/or may be arranged in any suitable shape and/or manner. In various embodiments, quantum computing grid 900 can be fabricated by any suitable nanofabrication and/or microfabrication technique on any suitable quantum computing substrate (eg, silicon substrate).

[00120] FIG. 10 shows a flowchart of an example non-limiting method 1000 that may facilitate mode-selective couplers for frequency collision reduction in accordance with one or more embodiments described herein.

[00121] In various embodiments, operation 1002 may include providing a control qubit (eg, 502). In various cases, such providing may be facilitated by any suitable micro-fabrication and/or nano-fabrication technique. In various cases, the control qubit can be provided on any suitable quantum computing substrate.

[00122] In various cases, operation 1004 couples the control qubit to a first target qubit (eg, 504) by a first mode-selective coupler (eg, 126) that facilitates A-mode coupling. steps may be included.

[00123] In various embodiments, operation 1006 couples the control qubit to a second target qubit (eg 506) by a second mode-selective coupler (eg 302) that facilitates B-mode coupling. steps may be included.

[00124] In various embodiments, operation 1008 directs the control qubit to a first microwave tone corresponding to the A-mode excitation frequency (eg, the A-mode transition frequency of the first target qubit 504). may include driving , thereby entangling the first target qubit with the control qubit.

[00125] In various cases, operation 1010 directs the control qubit to a second microwave tone corresponding to a B-mode excitation frequency (eg, a B-mode transition frequency of the second target qubit 506). It may include driving, thereby entangling the second target qubit with the control qubit.

[00126] As described herein, various embodiments of the present invention may provide mode-selective coupling between double-junction transmon qubits in a quantum computing lattice, which uses a cross-resonance gate. So even degenerate targets can be driven independently. By implementing a mode-selective coupler as described herein, various embodiments of the present invention use sets of at least 3 unique superconducting qubits rather than the typical sets of 5 unique superconducting qubits to get to the nearest -Can create neighbor-connected quantum computing lattices. This reduction in the number of sets of unique qubits may reduce the probability and/or spread of target-based frequency collisions occurring in a quantum computing lattice. In various embodiments, suppression and/or reduction of target-based frequency collisions can increase the production yield of multi-qubit devices and reduce the level of cross-talk between qubits.

[00127] In various embodiments, embodiments of the invention may be implemented in any suitable quantum computing grid employing any suitable level of grid connectivity. For example, in some cases, one can consider a next-nearest-neighbor-connected quantum computing lattice in which all non-perimetral qubits are coupled to eight neighboring qubits. In such cases, embodiments of the present invention may facilitate selective cross-resonance entanglement with sets of 5 unique qubits, rather than the usual 9 unique sets when next-nearest-neighbor connections are involved. .

[00128] In various embodiments, embodiments of the present invention reduce target-based frequency collisions in a square lattice of "TCQs" through mode-selective coupling between tunable coupler qubits ("TCQs"). can make it The mode-selective coupling may, in various embodiments, allow the cross-resonant entanglement gate to be driven between one type of excitation mode.

[00129] In various embodiments, a method of suppressing qubit collisions in a lattice of qubits includes providing tunable coupler qubits ("TCQs") having at least two junctions arranged in any suitable lattice configuration. can do. The method may further include coupling a TCQ in the lattice to two neighboring TCQs in the lattice via mode-selective coupling of a first type. The method may further include coupling a TCQ in the lattice to two other neighboring TCQs in the lattice via a second type of mode-selective coupling. In various embodiments, the first and second types of mode-selective coupling can reduce the set of qubit frequencies needed to avoid target-based frequency collisions.

[00130] To provide additional context for the various embodiments described herein, FIG. 11 and the discussion below refer to a suitable computing environment 1100 in which various embodiments of the embodiments described herein may be implemented. It is intended to provide a general description of Although the above embodiments have been described in the general context of computer executable instructions that can be executed on one or more computers, those skilled in the art will recognize that the embodiments may also be implemented in combination with other program modules and/or implemented as a combination of hardware and software. something to do.

[00131] In general, program modules include routines, programs, components, data structures, etc. that perform specific tasks or implement specific abstract data types. Moreover, those skilled in the art will understand that the methods of the present invention can be applied to single-processor or multiprocessor computer systems, mini computers, mainframe computers, Internet of Things (IoT) devices, distributed computing systems, personal computers, portable computing devices. (hand-held computing devices), microprocessor-based or programmable consumer electronics, and the like, each of which may be operatively coupled to one or more related devices. will be.

[00132] Embodiments shown herein may also be practiced in distributed computing environments where certain tasks are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, program modules may be located in both local and remote memory storage devices.

[00133] A computing device generally includes a variety of media, which may include computer-readable storage media, machine-readable storage media, and/or communications media. Including, the two terms are used differently in this specification as follows. Computer readable storage media or machine readable storage media can be any available storage media that can be accessed by a computer and includes both volatile and nonvolatile media, removable and non-removable media. By way of example (but not limitation), a computer readable storage medium or machine readable storage medium may be any storage medium for storing information such as computer readable or machine readable instructions, program modules, structured data or unstructured data. It may be implemented in terms of a method or technique.

[00134] A computer readable storage medium includes random access memory (RAM), read only memory (ROM), electrically erasable programmable read only memory, EEPROM), flash memory or other memory technology, compact disk read only memory (CD ROM), digital versatile disk (DVD), Blu-ray disc , BD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, solid may contain solid state drives or other solid state storage devices, or other tangible and/or non-transitory media that may be used to store desired information; It is not limited to this. In this regard, the terms "tangible" or "non-temporary" as applied herein to storage, memory, or computer-readable media are used as modifiers to all standard storage, It should be understood that no waiver of rights in the memory or computer readable medium is intended.

[00135] A computer readable storage medium may be accessed by one or more local or remote computing devices, eg, access requests, queries, or other data retrieval protocols, and perform various operations related to information stored by the medium. can do.

[00136] Communication media generally includes computer readable instructions, data structures, program modules or other structured or unstructured data in a data signal such as a modulated data signal (eg, a carrier wave or other transport mechanism). and includes any information delivery or transmission medium. The term "modulated data signal" or signals means a signal that has one or more characteristics set or changed in such a way as to encode information into the one or more signals. By way of example (but not limitation), communication media includes wired media such as a wired network or direct-wired connection and wireless media such as acoustic, RF, infrared and other wireless media. do.

[00137] Referring again to FIG. 11, an exemplary environment 1100 for implementing various embodiments of the features described herein is a computer including a computer 1102, a processing unit 1104 ( 1102), a system memory 1106 and a system bus 1108. System bus 1108 couples system components to processing unit 1104 , including but not limited to system memory 1106 . Processing unit 1104 may be any of a variety of commercially available processors. Dual microprocessors and other multiprocessor architectures may also be used for the processing unit 1104.

[00138] The system bus 1108 may include a memory bus (with or without a memory controller), a peripheral bus, and a local bus using any of a variety of commercially available bus architectures. It can be any of several types of bus structures that can be further interconnected. System memory 1106 includes ROM 1110 and RAM 1112 . The basic input/output system (BIOS) is stored in non-volatile memory such as ROM, erasable programmable read only memory (EPROM), and EEPROM. The BIOS includes basic routines that help transfer information between elements within the computer 1102, such as during startup. RAM 1112 may also include high-speed RAM, such as static RAM for data caching.

[00139] Computer 1102 includes an internal hard disk drive (HDD) 1114 (eg, EIDE, SATA), one or more external storage devices 1116 (eg, magnetic floppy disk drive, FDD). ) 1116, memory stick or flash drive reader, memory card reader, etc.) and drives 1120, e.g., solid state drives, optical disk drives disk drive), which can read from or write to the disk 1122, such as a CD-ROM disk, DVD, BD, or the like. Alternatively, if a solid state drive is included, disk 1122 is not included unless removed. Although internal HDD 1114 is shown as being located within computer 1102, internal HDD 1114 may be configured for external use in a suitable chassis (not shown). Also, although not shown in environment 1100, a solid state drive (SSD) may be used in addition to or instead of HDD 1114. HDD 1114, external storage device(s) 1116, and drive 1120 may be connected to system bus 1108 by HDD interface 1124, external storage device interface 1126, and drive interface 1128, respectively. there is. The interface 1124 for external drive implementation may include at least one or both of Universal Serial Bus (USB) and Institute of Electrical and Electronics Engineers (IEEE) 1394 interface technologies. Other external drive connection technologies are within the contemplation of the embodiments described herein.

[00140] Drives and related computer readable storage media provide nonvolatile storage of data, data structures, computer executable instructions, and the like. In the case of computer 1102, drives and storage media accommodate storage of all data in an appropriate digital format. Although the descriptions of computer-readable storage media above refer to each type of storage device, it should be understood that other types of computer-readable storage media, currently existing or developed in the future, may also be used in the exemplary operating environment. and furthermore, such a storage medium may contain computer executable instructions for performing the methods described herein.

[00141] A number of program modules, including an operating system 1130, one or more application programs 1132, other program modules 1134, and program data 1136 are stored in the drive and RAM 1112. It can be. All or part of the operating system, applications, modules and/or data may be cached in RAM 1112. The systems and methods described herein may be implemented using a variety of commercially available operating systems or combinations of operating systems.

[00142] Computer 1102 may optionally include emulation technologies. For example, a hypervisor (not shown) or other intermediary may emulate a hardware environment for operating system 1130, and the emulated hardware may optionally differ from the hardware shown in FIG. can In such an embodiment, operating system 1130 may include a virtual machine (VM) of multiple VMs hosted on computer 1102 . In addition, the operating system 1130 may provide a runtime environment such as a Java runtime environment or a .NET framework for the application 1132 . Runtime environments are consistent execution environments that allow applications 1132 to run on any operating system that includes a runtime environment. Similarly, operating system 1130 can support containers, and applications 1132 are lightweight, standalone versions of software including, for example, code, runtimes, system tools, system libraries, and settings for applications. It can be in the form of a container, which is a standalone or executable package.

[00143] Computer 1102 may also be activated with a secure module, such as a trusted processing module (TPM). For example, with a TPM, the boot component hashes the next boot component and waits until the result matches the secure value before loading the next boot component. This process can be performed at any layer of the code execution stack of the computer 1102, applied, for example, at the application execution level or at the operating system (OS) kernel level, thereby reducing the complexity of code execution. Enable security at all levels.

[00144] A user may enter commands and information into the computer 1102 through one or more wired/wireless input devices, such as a keyboard 1138, a touch screen 1140, and a pointing device such as a mouse 1142. can Other input devices (not shown) may include a microphone, an infrared (IR) remote control, a radio frequency (RF) remote control or other remote control, a joystick, a virtual reality controller and/or a virtual reality controller. Image input devices such as headsets, game pads, stylus pens, camera(s), gesture sensor input devices, vision movement sensor input devices , an emotion or facial detection device, a biometric input device such as a fingerprint or iris scanner, and the like. Input devices, emotion or face detection devices, biometric input devices such as fingerprint or iris scanners. These and other input devices are often connected to processing unit 1104 through input device interface 1144, which can be coupled to system bus 1108, but also includes a parallel port, IEEE 1394 serial port, game port, USB port , IR interface, Bluetooth® interface, etc.

[00145] A monitor 1146 or other type of display device may also be connected to the system bus 1108 through an interface such as a video adapter 1148. In addition to the monitor 1146, computers typically include other peripheral output devices (not shown) such as speakers, printers, and the like.

[00146] Computer 1102 may operate in a networked environment using logical connections via wired and/or wireless communications to one or more remote computers, such as remote computer(s) 1150. Remote computer(s) 1150 may be a workstation, server computer, router, personal computer, portable computer, microprocessor-based entertainment appliance, peer device, or other common network node. ), and generally includes most or all of the elements described in relation to computer 1102, although only memory/storage 1152 is shown for brevity. The illustrated logical connections include wired/wireless connections to a local area network (LAN) 1154 and/or a larger network (eg, a wide area network (WAN) 1156). These LAN and WAN networking environments are common in offices and businesses and facilitate facility enterprise-wide computer networks such as intranets, all of which can be connected to global communication networks such as the Internet. .

[00147] When used in a LAN networking environment, the computer 1102 may be connected to the local network 1154 through a wired and/or wireless communication network interface or adapter 1158. Adapter 1158 may facilitate wired or wireless communication to LAN 1154, which may also include a wireless access point (AP) deployed to communicate with adapter 1158 in a wireless mode. .

[00148] When used in a WAN networking environment, computer 1102 may include a modem 1160 or other means for establishing communications over WAN 1156, such as the Internet, to a communication server on WAN 1156. can be connected Modem 1160, which may be internal or external and a wired or wireless device, may be coupled to system bus 1108 through input device interface 1144. In a networked environment, program modules depicted on computer 1102 or portions thereof may be stored on remote memory/storage device 1152 . It should be understood that the network connections shown are exemplary and other means for establishing a communication link between computers may be used.

[00149] When used in a LAN or WAN networking environment, computer 1102 may be added to external storage device 1116 as described above, such as a network virtual machine that provides one or more storage or processing aspects of information, or its Instead, you can access a cloud storage system or other network-based storage system. In general, the connection between computer 1102 and the cloud storage system may be established via LAN 1154 or WAN 1156, for example by adapter 1158 or modem 1160, respectively. When computer 1102 is connected to an associated cloud storage system, external storage interface 1126 is provided by the cloud storage system just like any other type of external storage with the help of adapter 1158 and/or modem 1160. You can manage your storage. For example, external storage interface 1126 may be configured to provide access to cloud storage sources as if the cloud storage sources were physically connected to computer 1102 .

[00150] Computer 1102 is a printer, scanner, desktop and/or portable computer, portable data assistant, communications satellite, any equipment or location associated with a radio detectable tag (e.g., kiosk, newspaper). It may be operable to communicate with any wireless device or entity arranged operably in wireless communication, such as a news stand, store shelf, etc.), and a telephone. This may include Wireless Fidelity (Wi-Fi) and Bluetooth® wireless technologies. Thus, the communication may be a predefined structure like an existing network or simply an ad hoc communication between at least two devices.

[00151] The present invention may be a system, method, apparatus and/or computer program product at a possible technical level of integration. A computer program product may include a computer readable storage medium (or medium) having computer readable program instructions for causing a processor to perform an embodiment of the invention. A computer readable storage medium may be a tangible device capable of holding and storing instructions for use by an instruction execution device. A computer-readable storage medium may be, for example, but not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination thereof. A list (not exhaustive) of more specific examples of computer readable storage media may also include: That is, portable computer diskettes, hard disks, dynamic or static random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (erasable programmable read-only memory (EPROM or flash memory), magnetic storage device, portable compact disc read-only memory (CD-ROM), digital versatile disk (DVD) ), mechanically encoded devices such as memory sticks, floppy disks, punch-cards, or convex structures in grooves with written instructions, and any suitable combination of the foregoing. As used herein, computer readable storage media refers to radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through a waveguide or other transmission medium (e.g., pulses of light passing through a fiber optic cable), or wires Transient signals, such as electrical signals transmitted through

[00152] Computer readable program instructions described herein may be transferred from a computer readable storage medium to respective computing/processing devices via a communications network, such as, for example, the Internet, local area network, wide area network, and/or wireless communications network; or downloaded to an internal computer or external storage device. The network may include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers, and/or edge servers. A network adapter card or network interface in each computing/processing device receives computer readable program instructions from the network and transmits computer readable program instructions for storage on a computer readable storage medium in each computing/processing device. Computer readable program instructions for performing the operations of the present invention may include assembler instructions, instruction-set-architecture (ISA) instructions, machine instructions, machine dependent instructions, and the like. instructions, microcode, firmware instructions, state-setting data, or source code or object code written in any combination of one or more programming languages. The programming languages include object oriented programming languages such as Smalltalk, C++, etc., and procedural programming languages such as the "C" programming language or similar programming languages. The computer readable program instructions may execute entirely on the user's computer, partly on the user's computer, partly on the user's computer and partly on a remote computer, as a stand-alone software package, or partly on a remote computer. Or it can run entirely on a server or cluster of servers. In the latter scenario, the remote computer may be connected to the user's computer through some type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (e.g. , over the Internet using an Internet Service Provider). In some embodiments, to perform aspects of the embodiment(s) of the invention, for example programmable logic circuitry, field-programmable gate arrays (FPGAs) ), or electronic circuitry, including programmable logic arrays (PLA), by using state information of computer readable program instructions to personalize the electronic circuitry so that the computer readable program commands can be executed.

[00153] Embodiments of the invention are described herein with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products. It will be appreciated that each block, and combinations of blocks, of the flowchart descriptions and/or block diagrams in the flowchart descriptions and/or block diagrams may be implemented by computer readable program instructions. These computer readable program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing device to create a machine, thereby creating a computer or other program. When executed through a processor of a capable data processing device, the instructions cause the instructions to create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. These computer readable program instructions may also be stored in computer readable storage, which may direct a computer, programmable data processing apparatus, and/or other devices to function in a particular manner. Thus, a computer readable storage medium having instructions stored therein may include an article of manufacture containing instructions implementing aspects of the function/operation specified in the block or blocks of a flowchart and/or block diagram. Computer readable program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable apparatus, or other device in a computer implemented process. can be created. Thus, instructions executed on a computer, other programmable apparatus, or other device cause the block or blocks of a flowchart and/or block diagram to implement the functions/acts specified in the blocks.

[00154] The flowcharts and block diagrams in the drawings show the architecture, function, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the invention. In this regard, each block in a flowchart or block diagrams may represent a module, segment, or portion of instructions, which includes one or more executable instructions for implementing the specified logical function(s). . In some other implementations, functions described in blocks may occur out of the order in which they are described in the figures. For example, two blocks shown in succession may, in fact, occur substantially concurrently, or the blocks may sometimes be executed in reverse order depending on the function involved. In addition, each block in the block diagrams and/or flowchart figure, and combinations of blocks in the block diagrams and/or flowchart figure, may perform specified functions or operations or perform combinations of dedicated hardware and computer instructions. It should be noted that it may be implemented by dedicated hardware based systems.

[00155] Although the above subject matter has been described in the general context of a computer and/or computer implemented instructions of a computer program product running on a computer, one skilled in the art will recognize that the present disclosure may also be implemented or implemented in combination with other program modules. something to do. Generally, program modules include routines, programs, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Moreover, one skilled in the art will understand that the computer implemented method of the present invention can be used in single-processor or multi-processor computer systems, mini-computing devices, mainframe computers as well as computers, portable computing devices (eg PDAs, telephones), microprocessor-based or programmable It will be appreciated that other computer system configurations may be implemented, including consumer or industrial electronics and the like. The illustrated aspects may also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a communications network. However, some, if not all, aspects of this disclosure may be implemented on standalone computers. In a distributed computing environment, program modules may be located on both local and remote memory storage devices.

[00156] As used in this application, the terms “component”, “system”, “platform”, “interface”, etc. may refer to and/or include a computer-related entity or an entity related to an operating machine having one or more specific functions. can Subjects disclosed herein may be hardware, a combination of hardware and software, software, or software in execution. A component can be, but is not limited to, a process running on a processor, a processor, an object, an executable, a thread of execution, a program, and/or a computer. For example, both an application running on a server and a server can be components. One or more components can reside within a process and/or thread of execution and a component can be localized on one computer and/or distributed between two or more computers. In another example, each component can execute from various computer readable media having various data structures stored thereon. A component may communicate via local and/or remote processes according to signals with one or more data packets (e.g., local systems, distributed systems, and/or signals via signals to other systems and the Internet). data from one component that interacts over a network, such as As another example, a component may be a device with specific functions provided by mechanical parts actuated by electrical or electronic circuitry actuated by a software or firmware application executed by a processor. In such cases, the processor may be internal or external to the device and may execute at least part of a software or firmware application. As another example, a component can be a device that provides certain functionality without mechanical parts through electronic components, where the electronic component includes a processor or other means for executing software or firmware that provides, at least in part, the functionality of the electronic component. can be included In one aspect, a component may emulate an electronic component via a virtual machine, for example within a cloud computing system.

[00157] Also, the term "or" means an inclusive "or" rather than an exclusive "or". That is, unless otherwise specified or clear from the context, “X employs A or B” means a natural inclusive permutation. That is, when X employs A, X employs B, or X employs both A and B, "X employs either A or B" is satisfied in any of the preceding cases. Moreover, as used in this specification and the accompanying drawings, the articles "a" and "an" should generally be interpreted to mean "one or more" unless otherwise specified and should be construed explicitly as referring to the singular in the context. do. As used herein, the terms "example" and/or "exemplary" are used to mean serving as an example, instance, or illustration. For the avoidance of doubt, the subject matter disclosed herein is not limited by these examples. In addition, any aspect or design described herein as an “example” and/or “exemplary” should not necessarily be construed as preferred or advantageous over other aspects or designs, and equivalent exemplary structures and techniques known to those skilled in the art. does not mean excluding

[00158] As used herein, the term "processor" includes substantially single-core processors; a single processor with software multithreaded execution; multi-core processors; multi-core processors with software multithreaded execution; multi-core processor with hardware multithreading technology; parallel platforms; and any computing processing unit or device including, but not limited to, a parallel platform with distributed shared memory. Additionally, a processor may include an integrated circuit, an application specific integrated circuit (ASIC), a digital signal processor (DSP), a field programmable gate array, FPGA), a programmable logic controller (PLC), a complex programmable logic device (CPLD), a discrete gate or transistor logic, discrete hardware components (discrete hardware components), or any combination thereof designed to perform the functions described herein. Additionally, the processors will utilize nano-scale architectures such as molecular and quantum-dot based transistors, switches and gates to optimize space usage or improve the performance of user equipment. may, but is not limited thereto. A processor may also be implemented as a combination of computing processing units. As used herein, "store", "storage", "data store", "data storage", "database" and substantially all other information storage components related to the operation and functioning of the component are referred to as "memory component", "memory". It is used to refer to the implemented subject or the components constituting the memory. It should be understood that the memory and/or memory components described herein may be volatile memory or non-volatile memory, and may include both volatile and non-volatile memory. By way of example (but not limitation), non-volatile memory includes read only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), It may include electrically erasable ROM (EEPROM), flash memory, or nonvolatile random access memory (RAM) (eg, ferroelectric RAM (FeRAM)). Volatile memory can include, for example, RAM, which can act as external cache memory. By way of example (but not limitation), RAM includes synchronous RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (SDRAM), DDR SDRAM), enhanced SDRAM (ESDRAM), Synchlink DRAM (SLDRAM), direct Rambus RAM (DRRAM), direct Rambus dynamic RAM (DRDRAM), and Rambus dynamic RAM It is available in various forms, such as RAM (Rambus dynamic RAM, RDRAM). Additionally, memory components of the systems or computer implemented methods disclosed herein are intended to include, but are not limited to, these and any other suitable types of memory.

[00159] What has been described above includes simple examples of systems and computer-implemented methods. Of course, it is not possible to describe every possible combination of components or computer implemented methods for purposes of describing the present invention, but those skilled in the art will recognize that many additional combinations and permutations of the present invention are possible. In addition, to the extent that terms such as “includes,” “has,” “possesses,” etc. are used in the description, claims, appendices, and drawings, these terms When used as a transitional word in a scope, these terms are intended to be inclusive in a manner similar to terms interpreting "comprising" as "comprising".

[00160] The description of the various embodiments has been presented for illustrative purposes, but is not a complete description or limitation of the embodiments of the present invention. Numerous variations and modifications will become apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terms used herein have been chosen to best describe the principles of the embodiments, practical applications or technical improvements to the technology found on the market, or to enable those skilled in the art to understand the embodiments disclosed herein.

Claims (20)

In a device, the device:
a control qubit;
a first target qubit coupled to the control qubit by a first mode-selective coupler that facilitates A-mode coupling; and
a second target qubit coupled to the control qubit by a second mode-selective coupler that facilitates B-mode coupling;
device. The method of claim 1, wherein the control qubit, the first target qubit, and the second target qubit are two-junction transmon qubits.
device. 3. The method of claim 2, wherein the first mode-selective coupler comprises a capacitor capacitively coupling a middle capacitor pad of the control qubit to a middle capacitor pad of the first target qubit.
device. 4. The method of claim 3, wherein the capacitor has a capacitance that is less than shunting capacitance values of the control qubit and less than shunting capacitance values of the first target qubit.
device. The method of any one of claims 1 to 4 and the features of claim 2, wherein the second mode-selective coupler is configured to capacitate an end capacitor pad of the control qubit to an end capacitor pad of the second target qubit. a second capacitor capacitively coupling an end capacitor pad of the control qubit to a middle capacitor pad of the second target qubit;
device. 6. The method of claim 5, wherein the first capacitor has a first capacitance that is less than shunting capacitance values of the control qubit and less than shunting capacitance values of the second target qubit, and wherein the second capacitor is of the first capacitor with half the second capacitance
device. 7. The method of any one of claims 1 to 6, wherein the first target qubit and the second target qubit are degenerate targets.
device. 8. The method of claim 7, wherein the first target when the control qubit is driven by a first microwave tone corresponding to an A-mode excitation frequency of the degenerate targets. A qubit is entangled with the control qubit, and when the control qubit is driven by a second microwave tone corresponding to the B-mode excitation frequency of the degenerate targets, the second target qubit is entangled with the control qubit.
device. In the method, the method comprises:
providing a control qubit;
coupling the control qubit to a first target qubit by a first mode-selective coupler that facilitates A-mode coupling; and
coupling the control qubit to a second target qubit by a second mode-selective coupler that facilitates B-mode coupling.
method. 10. The method of claim 9, wherein the control qubit, the first target qubit, and the second target qubit are two-junction transmon qubits.
method. 11. The method of claim 10, wherein the first mode-selective coupler comprises a capacitor capacitively coupling a middle capacitor pad of the control qubit to a middle capacitor pad of the first target qubit.
method. 12. The method of claim 11, wherein the capacitor has a capacitance that is less than shunting capacitance values of the control qubit and less than shunting capacitance values of the first target qubit.
method. 11. The method of any one of claims 9 to 12 and the features of claim 10, wherein the second mode-selective coupler is configured to capacitate an end capacitor pad of the control qubit to an end capacitor pad of the second target qubit. a second capacitor capacitively coupling an end capacitor pad of the control qubit to a middle capacitor pad of the second target qubit;
method. 14. The method of claim 13, wherein the first capacitor has a first capacitance that is less than shunting capacitance values of the control qubit and less than shunting capacitance values of the second target qubit, and wherein the second capacitor is of the first capacitor with half the second capacitance
method. 15. The method of any one of claims 9 to 14, wherein the first target qubit and the second target qubit are degenerate targets.
method. 16. The method of claim 15, wherein the method:
driving the control qubit with a first microwave tone corresponding to the A-mode excitation frequency of the degenerate targets, and thereby entangling the first target qubit with the control qubit; and
driving the control qubit with a second microwave tone corresponding to the B-mode excitation frequency of the degenerate targets, and thereby entangling the second target qubit with the control qubit
method. An apparatus comprising:
a first mode-selective coupler that facilitates A-mode coupling between the control qubit and the first target qubit; and
A second mode-selective coupler facilitating B-mode coupling between the control qubit and a second target qubit.
Device. 18. The method of claim 17, wherein the first mode-selective coupler comprises a capacitor coupling a middle capacitor pad of the control qubit to a middle capacitor pad of the first target qubit, wherein the capacitance of the capacitor is the control qubit. less than the shunting capacitance values of the second target qubit and less than the shunting capacitance values of the second target qubit.
Device. 19. The method of any one of claims 17 to 18, wherein the second mode-selective coupler comprises a first capacitor coupling an end capacitor pad of the control qubit to an end capacitor pad of the second target qubit; and a second capacitor coupling an end capacitor pad of the control qubit to a middle capacitor pad of the second target qubit, wherein a first capacitance of the first capacitor is less than shunting capacitance values of the control qubit and the first capacitance of the first capacitor is less than shunting capacitance values of the control qubit. less than shunting capacitance values of 2 target qubits, and the second capacitance of the second capacitor is half of the first capacitance
Device. 20. The method of any one of claims 17 to 19, wherein the first target qubit and the second target qubit are degenerate targets, and the control qubit is an A-mode excitation frequency of the degenerate targets. The first target qubit is entangled with the control qubit when driven by a first microwave tone corresponding to , and the control qubit is driven by a second microwave tone corresponding to the B-mode excitation frequency of the degenerate targets. When the second target qubit is entangled with the control qubit
Device.

Images